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1
Wołynski, Waldemar. "Minimal Sample Size in the Group Classification Problem." Journal of Classification 22, no. 1 (2005): 49–58. http://dx.doi.org/10.1007/s00357-005-0005-8.
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Grjibovski, A. M., M. A. Gorbatova, A. N. Narkevich, and K. A. Vinogradov. "Required sample size for comparing means in two paired samples." Marine Medicine 6, no. 4 (2021): 82–88. http://dx.doi.org/10.22328/2413-5747-2020-6-4-82-88.
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This paper continues our series of articles for beginners on required sample size for the most common basic statistical tests used in biomedical research. The most common statistical test for comparing means in paired samples is Student’s paired t-test. In this paper we present a simple algorithm for calculating required sample size for comparing two means in paired samples. As in our earlier papers we demonstrate how to perform calculations using WinPepi and Stata software. Moreover, we have created a table with calculated minimal sample sizes required for using Student’s t-tests for different scenarios with the confidence level of 95% and statistical power of 80%.
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Grjibovski, A. M., M. A. Gorbatova, A. N. Narkevich, and K. A. Vinogradov. "Required sample size for comparing two independent means." Marine Medicine 6, no. 2 (2020): 106–13. http://dx.doi.org/10.22328/2413-5747-2020-6-2-106-113.
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Sample size calculation in a planning phase is still uncommon in Russian research practice. This situation threatens validity of the conclusions and may introduce Type I error when the false null hypothesis is accepted due to lack of statistical power to detect the existing difference between the means. Comparing two means using unpaired Students’ ttests is the most common statistical procedure in the Russian biomedical literature. However, calculations of the minimal required sample size or retrospective calculation of the statistical power were observed only in very few publications. In this paper we demonstrate how to calculate required sample size for comparing means in unpaired samples using WinPepi and Stata software. In addition, we produced tables for minimal required sample size for studies when two means have to be compared and body mass index and blood pressure are the variables of interest. The tables were constructed for unpaired samples for different levels of statistical power and standard deviations obtained from the literature.
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Pareniuk, Dmytro. "Method of evaluation of the minimal sample size for acoustical signal therapy monitored via electroencephalographic activity of human brain." ScienceRise, no. 2 (April 30, 2021): 75–82. https://doi.org/10.21303/2313-8416.2021.001736.
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The aim of the study. Improvement of the preparation to the acoustical signal therapy test or experiment of electroencephalographic activity of human brain and validation of the specified test results. The problem to be solved. Estimation of the minimal possible sample size for maintaining needed research accuracy in the research field of the electroencephalographic activity of human brain via monitoring of the brainwave patterns during exposure to the musical signal. Main scientific results. New method for selection minimal passable sample size for brainwave pattern studies is presented. Example of application of method for one rhythm of the brainwaves (delta-rhythm) is shown. Perspective way of obtaining clinically valuable differences between test group results was acquired. Differences between mean values for groups of results of different types of music and stress factor exposure are presented. The area of practical use of the research results. Research facilities dedicated to the study of electroencephalographic activity of human brain and medical facilities and institutions, dedicated to the treatment of pathologies of the central nervous system, brain damage, stress, and progressive post-stress action psychological state restoration. An innovative technological product. Dedicated method for quick estimation of minimal passable sample size for brainwave pattern studies, which is recommended for usage in the studies of the implementation of music therapy. The area of application of an innovative technological product. Electroencephalographic activity of human brain study via brainwave pattern research. Clinical practice of application of a music therapy.
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Kostic, Aleksandar, Svetlana Ilic, and Petar Milin. "Probability estimate and the optimal text size." Psihologija 41, no. 1 (2008): 35–51. http://dx.doi.org/10.2298/psi0801035k.
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Reliable language corpus implies a text sample of size n that provides stable probability distributions of linguistic phenomena. The question is what is the minimal (i.e. the optimal) text size at which probabilities of linguistic phenomena become stable. Specifically, we were interested in probabilities of grammatical forms. We started with an a priori assumption that text size of 1.000.000 words is sufficient to provide stable probability distributions. Text of this size we treated as a "quasi-population". Probability distribution derived from the "quasi-population" was then correlated with probability distribution obtained on a minimal sample size (32 items) for a given linguistic category (e.g. nouns). Correlation coefficient was treated as a measure of similarity between the two probability distributions. The minimal sample was increased by geometrical progression, up to the size where correlation between distribution derived from the quasi-population and the one derived from an increased sample reached its maximum (r=1). Optimal sample size was established for grammatical forms of nouns, adjectives and verbs. General formalism is proposed that allows estimate of an optimal sample size from minimal sample (i.e. 32 items).
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Pérez-Llorca, Marina, Erola Fenollosa, Roberto Salguero-Gómez, and Sergi Munné-Bosch. "What Is the Minimal Optimal Sample Size for Plant Ecophysiological Studies?" Plant Physiology 178, no. 3 (2018): 953–55. http://dx.doi.org/10.1104/pp.18.01001.
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Tanner, D. Q., J. D. Stednick, and W. C. Leininger. "Minimal herd sample size for determination of blood copper status of cattle." Journal of the American Veterinary Medical Association 192, no. 8 (1988): 1074–76. https://doi.org/10.2460/javma.1988.192.08.1074.
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Summary Copper is required by cattle for synthesis of numerous proteins and enzymes. Copper deficiency in cattle results in a variety of signs ranging from weight loss to diarrhea. In the fall of 1984 and 1985, blood samples were collected from 22 cattle herds near Gunnison, Colo. Approximately one third of the herds were classified as copper deficient (ie, mean serum copper concentration <0.6 mg/L). The inherent variability of serum copper concentrations within a herd mandates the determination of the minimal number of cattle to be tested to properly assess the blood copper status of a herd. Coefficients of variation for serum copper concentration were used to calculate a minimal sample size, with a 95% confidence interval for each herd. Minimal sample size ranged from 3 to 55 cattle/herd (ie, 1 to 22% of the herd); this finding suggested that the usual procedure of testing 10% of the herd may be inappropriate.
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Neely, J. Gail, Ron J. Karni, Samuel H. Engel, Patrick L. Fraley, Brian Nussenbaum, and Randal C. Paniello. "Practical guides to understanding sample size and minimal clinically important difference (MCID)." Otolaryngology–Head and Neck Surgery 136, no. 1 (2007): 14–18. http://dx.doi.org/10.1016/j.otohns.2006.11.001.
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Grjibovski, A. M., M. A. Gorbatova, A. N. Narkevich, and K. A. Vinogradov. "REQUIRED SAMPLE SIZE FOR CORRELATION ANALYSIS." Marine Medicine 6, no. 1 (2020): 101–6. http://dx.doi.org/10.22328/2413-5747-2020-6-1-101-106.
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Sample size calculation prior to data collection is still relatively rare in Russian research practice. This situation threatens validity of the conclusion of many projects due to insufficient statistical power to estimate the parameters of interest with desired precision or to detect the differences of interest. Moreover, in a substantial proportion of cases where sample size calculations are performed simplified formulas with assumption of a normal distribution of the studied variables are used in spite of the fact that this assumption does not hold for many research questions in biomedical research. Correlation analysis is still one of the most commonly used methods of statistical analysis used in Russia. Pearson’s correlation coefficient despite its well-known limitations appears in a greater proportion of publications that non-parametric coefficients. We calculated minimal sample sizes for the parametric Pearson’s coefficient as well its non-parametric alternatives — Spearman’s rho and Kendall’s tau-b correlation coefficients to assist junior researchers with the tool to be able to plan data collection and analysis for several types of data, various expected strengths of associations and research questions. The results are presented in ready-for-use tables with required sample size for the three abovementioned coefficients within the range from 0,10 through 0,90 by 0,05 for statistical power 0,8 and 0,9 and alpha-error or 5% as well as for estimation of the same correlation coefficients with the 95% confidence intervals width equal to 0,1 and 0,2.
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Buckley, W. T., J. Huang, and M. A. Monreal. "Ethanol emission seed vigour test for canola: minimal effects from variations in incubation conditions, sample size and seed moisture content." Seed Science and Technology 41, no. 2 (2013): 270–80. http://dx.doi.org/10.15258/sst.2013.41.2.09.
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Dalgaard, M. K., A. E. Christensen, and M. K. Kjeldsen. "What minimal detectable effect size is in your power – An inverted sample size formular for survival data." European Psychiatry 66, S1 (2023): S538—S539. http://dx.doi.org/10.1192/j.eurpsy.2023.1139.
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IntroductionPower calculations are widely used in the conduct of clinical trials and are often required in funding applications and approvals. There is a recent debate on the role of power calculations in observational studies on existing data with (Hernán J Clin Epidemiol 2022; 144 203-205) and (Moris and Smeden J Clin Epidemiol 2022; 142 261-263) emphasizing the need for planning for all study types without risking discarding imprecise but otherwise relevant studies. In the current study, we construct a graph useful in the planning of a wide range of studies with survival data. We map the minimal detectable effect (MDE) for any possible number of events with a dichotome exposure varying the proportion assigned to the exposure groups.ObjectivesTo provide a visual tool relating the sample size, more precisely the number of events, and the MDE for survival data in unbalanced designs.MethodsThe visualization is based on the formulas used by Stata’s power logrank function by (Schoenfeld Biometrics 1983; 39 499-503) and (Freedman Statistics in medicine 1982; 1 121-129), and the MDE is mapped as a function of the number of events. Furthermore, we apply this to an ongoing project on data from the Danish national registers, comparing the risk of developing polycystic ovary syndrome (PCOS) associated with treatment with valproic acid in a population with bipolar disorder or epilepsy.ResultsPreliminary results (Fig. 1) show, as expected, that a larger sample size is required to obtain an MDE close to one. Also, the MDE increases when the assignment among groups is skewed. Moreover, we find a relevant minimal detectable HRR of 1.78 for developing PCOS in a population of 13,839 patients with bipolar disorder or epilepsy, exposed to valproic acid versus those not exposed to valproic acid, with a total of 203 cases of PCOS.Fig. 1 shows the minimal detectable effect size as a function of the number of events, with α = 0.05 and a power of 1 - β = 0.8, for various assignment ratios φ = PT/PC, where PT and PC are the proportions of patients assigned to the treatment group and the control group, respectively.Image:ConclusionsThe current visualization and corresponding calculation can be used to guide decisions in the design phase of both observational studies as well as in clinical trials. For observational studies, the sample size, or equivalently, the number of events, could well be fixed, and the MDE may help assess the clinical relevance of conducting the study as in the example with PCOS data. The curves can also provide insight into which efforts might lower the MDE, e.g., whether a small increase in sample size or a different assignment proportion would be most beneficial based on a given sample size.Disclosure of InterestNone Declared
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Baggaley, Andrew R. "Heterogeneous correlations and estimates of required sample size in factor analysis." Multivariate Experimental Clinical Research Journal 8, no. 1 (1986): 161–63. http://dx.doi.org/10.62704/10057/17630.
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Factor matrices with various patterns of loadings were constructed to study the effect of heterogeneous correlations on estimates of the minimal number of subjects in factor analysis. The tabled values of appropriate ratios of number of subjects to number of variables presented in a previous article were shown to furnish rather accurate estimates over the range of factorial patterns studied.
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Wang, Zhi Ming. "Reliability Assessment Test Design for Numerical Control Machine Tools." Advanced Materials Research 542-543 (June 2012): 1218–21. http://dx.doi.org/10.4028/www.scientific.net/amr.542-543.1218.
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According to the required interval estimation precision of mean time between failures (MTBF) and reliability for numerical control (NC) machine tools, where failure processes can be described by the power law process model, the minimal testing truncated time and sample size of the reliability assessment test are given using Fisher information matrix method. The results show that there are two main factors which affect the truncated time and sample size. They are the log ratio of upper bound to lower bound and confidence of interval estimation for reliability indices, respectively. Among them, the minimal sample size increases significantly as the improvement of required precision of interval estimation for reliability indices and confidence increases, but the minimal testing truncated time is less affected by these two factors.
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Patel, J. A., and H. C. Patel. "Minimal Complete Class of Linear Unbiased Estimators of Population Mean for a Special Sampling Design1." Calcutta Statistical Association Bulletin 38, no. 1-2 (1989): 71–82. http://dx.doi.org/10.1177/0008068319890106.
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In this paper we give a complete description of the minimal complete subclass of C the class of all homogeneous linear unbiased estimators of a finite population mean for the extremely special case of taking sample of size 2 units from a population of size 4, where only samples containing units ( U1, Ui+ 1) have equal positive probability.
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Blum, Michael G. B., and Olivier François. "Minimal clade size and external branch length under the neutral coalescent." Advances in Applied Probability 37, no. 3 (2005): 647–62. http://dx.doi.org/10.1239/aap/1127483740.
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Given a sample of genes taken from a large population, we consider the neutral coalescent genealogy and study the theoretical and empirical distributions of the size of the smallest clade containing a fixed gene. We show that the theoretical distribution is strongly related to a Yule distribution of parameter 2, and that the empirical count statistics are asymptotically Gaussian as the number of genes grows to infinity. Then we consider external branches of the coalescent tree, and describe their lengths. Using the infinitely many sites model of mutation, we also describe the conditional distribution of the external branch lengths, given the number of pairwise differences between a reference DNA sequence and the sequence of one closest relative in the sample.
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Blum, Michael G. B., and Olivier François. "Minimal clade size and external branch length under the neutral coalescent." Advances in Applied Probability 37, no. 03 (2005): 647–62. http://dx.doi.org/10.1017/s0001867800000409.
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Given a sample of genes taken from a large population, we consider the neutral coalescent genealogy and study the theoretical and empirical distributions of the size of the smallest clade containing a fixed gene. We show that the theoretical distribution is strongly related to a Yule distribution of parameter 2, and that the empirical count statistics are asymptotically Gaussian as the number of genes grows to infinity. Then we consider external branches of the coalescent tree, and describe their lengths. Using the infinitely many sites model of mutation, we also describe the conditional distribution of the external branch lengths, given the number of pairwise differences between a reference DNA sequence and the sequence of one closest relative in the sample.
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Ferdila, Ferdila, Ita Mustika, and Sri Martina. "Pengaruh Firm Size, Likuiditas, Leverage Dan Profitabilitas Terhadap Nilai Perusahaan Pada Perusahaan Manufaktur Sub Sektor Barang Konsumsi Yang Terdaftar Di Bursa Efek Indonesia." Owner 7, no. 4 (2023): 3274–84. http://dx.doi.org/10.33395/owner.v7i4.1883.
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This study examines how business size, liquidity, leverage, and profitability affect firm value in Indonesia Stock Exchange-listed supply products manufacturing companies between 2019 and 2021. Earlier corporate value study had mixed results. Therefore, more research is needed to retest company worth. The survey sampled 47 consumer products manufacturers. For the three-year observation period (2019–2021), 13 business samples were purposefully sampled with 39 observations. The Indonesian Stock Exchange website provided the sample businesses and research data. Research data obtained from the Indonesian Stock Exchange website, where sample businesses were found. The data analysis approach began with descriptive statistics, classical assumption test, multiple regression analysis, and hypothesis testing. Corporate size, liquidity, leverage, and profitability affect firm value. According to research, only profitability increases firm worth significantly. Significant to firm value. Liquidity boosts corporate value but not significantly. Leverage and firm size have minimal impact on firm value
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Thomas, Hoben. "Effect Size Standard Errors for the Non-Normal Non-Identically Distributed Case." Journal of Educational Statistics 11, no. 4 (1986): 293–303. http://dx.doi.org/10.3102/10769986011004293.
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Suppose there are k independent studies and for each study the experimental and control groups have been sampled from independent but essentially arbitrary populations. The problem is to construct a plausible standard error of the effect size mean (effect sizes are standardized experimental-control group mean differences) when given only minimal sample statistic information. Standard errors based on the sample standard error, or bootstrap, will typically be much too large and have very large variance. A normal theory estimator may prove practically useful in more general settings. Asymptotic distribution-free estimators are provided for two cases.
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Costa, Leonardo S. da, Nathana S. Corneleo, and Valdir M. Stefenon. "Conservation of Forest Biodiversity: how sample size affects the estimation of genetic parameters." Anais da Academia Brasileira de Ciências 87, no. 2 (2015): 1095–100. http://dx.doi.org/10.1590/0001-3765201520140064.
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Efficient designs are crucial for population genetic studies on forest species. In this study we employed individual based simulations aiming to evaluate what fraction of a population should be sampled to obtain confident estimations of allelic richness and of inbreeding coefficient in population genetic surveys. The simulations suggest that at least 10% of the total population has to be sampled to ensure reliable estimations of allelic richness and inbreeding coefficient. This approach will allow the confidence of the genetic parameters estimations of a larger number of populations, based on a minimal sample within each one.
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Kaczmarek, Łukasz Dominik, Yufeng Zhao, Heinz Konietzky, Tomasz Wejrzanowski, and Michał Maksimczuk. "Numerical Approach in Recognition of Selected Features of Rock Structure from Hybrid Hydrocarbon Reservoir Samples Based on Microtomography." Studia Geotechnica et Mechanica 39, no. 1 (2017): 13–26. http://dx.doi.org/10.1515/sgem-2017-0002.
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Abstract The study employs numerical calculations in the characterization of reservoir sandstone samples based on high-resolution X-ray computed microtomography. The major goals were to determine porosity through pore size distribution, permeability characterization through pressure field, and structure impact on rock strength by simulation of a uniaxial compression test. Two Miocene samples were taken from well S-3, located in the eastern part of the Carpathian Foredeep. Due to the relation between sample size and image resolution, two X-ray irradiation series with two different sample sizes were performed. In the first approach, the voxel side was 27 μm and in the second it was up to 2 μm. Two samples from different depths have been studied here. Sample 1 has petrophysical features of conventional reservoir deposits, in contrast to sample 2. The approximate grain size of sample 1 is in the range 0.1-1.0 mm, whereas for sample 2 it is 0.01-0.1 mm with clear sedimentation lamination and heterogenic structure. The porosity, as determined by μCT, of sample 1 is twice (10.3%) that of sample 2 (5.3%). The equivalent diameter of a majority of pores is less than 0.027 mm and their pore size distribution is unimodal right-hand asymmetrical in the case of both samples. In relation to numerical permeability tests, the flow paths are in the few privileged directions where the pressure is uniformly decreasing. Nevertheless, there are visible connections in sample 1, as is confirmed by the homogenous distribution of particles in the pore space of the sample and demonstrated in the particle flow simulations. The estimated permeability of the first sample is approximately four times higher than that of the second one. The uniaxial compression test demonstrated the huge impact of even minimal heterogeneity of samples in terms of micropores: 4-5 times loss of strength compared to the undisturbed sample. The procedure presented shows the promising combination of microstructural analysis and numerical simulations. More specific calculations of lab tests with analysis of variable boundary conditions should be performed in the future.
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Yu, Jianxing, Shiqi Wang, and Jian Yin. "Adaptive Cross-Lingual Question Generation with Minimal Resources." Computer Journal 64, no. 7 (2021): 1056–68. http://dx.doi.org/10.1093/comjnl/bxab106.
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Abstract The task of question generation (QG) aims to create valid questions and correlated answers from the given text. Despite the neural QG approaches have achieved promising results, they are typically developed for languages with rich annotated training data. Because of the high annotation cost, it is difficult to deploy to other low-resource languages. Besides, different samples have their own characteristics on the aspects of text contextual structure, question type and correlations. Without capturing these diversified characteristics, the traditional one-size-fits-all model is hard to generate the best results. To address this problem, we study the task of cross-lingual QG from an adaptive learning perspective. Concretely, we first build a basic QG model on a multilingual space using the labelled data. In this way, we can transfer the supervision from the high-resource language to the language lacking labelled data. We then design a task-specific meta-learner to optimize the basic QG model. Each sample and its similar instances are viewed as a pseudo-QG task. The asking patterns and logical forms contained in the similar samples can be used as a guide to fine-tune the model fitly and produce the optimal results accordingly. Considering that each sample contains the text, question and answer, with unknown semantic correlations among them, we propose a context-dependent retriever to measure the similarity of such structured inputs. Experimental results on three languages of three typical data sets show the effectiveness of our approach.
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Zhivulin, Vladimir E., Evgeniy A. Trofimov, Svetlana A. Gudkova, et al. "Polysubstituted High-Entropy [LaNd](Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3 Perovskites: Correlation of the Electrical and Magnetic Properties." Nanomaterials 11, no. 4 (2021): 1014. http://dx.doi.org/10.3390/nano11041014.
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La-, Nd- and La/Nd-based polysubstituted high-entropy oxides (HEOs) were produced by solid-state reactions. Composition of the B-site was fixed for all samples (Cr0.2Mn0.2Fe0.2Co0.2Ni0.2) with varying of A-site cation (La, Nd and La0.5Nd0.5). Nominal chemical composition of the HEOs correlates well with initial calculated stoichiometry. All produced samples are single phase with perovskite-like structure. Average particle size is critically dependent on chemical composition. Minimal average particle size (~400 nm) was observed for the La-based sample and maximal average particle size (5.8 μm) was observed for the Nd-based sample. The values of the configurational entropy of mixing for each sample were calculated. Electrical properties were investigated in the wide range of temperatures (150–450 K) and frequencies (10−1–107 Hz). Results are discussed in terms of the variable range hopping and the small polaron hopping mechanisms. Magnetic properties were analyzed from the temperature and field dependences of the specific magnetization. The frustrated state of the spin subsystem was observed, and it can be a result of the increasing entropy state. From the Zero-Field-Cooling and Field-Cooling regimes (ZFC-FC) curves, we determine the <S> average and Smax maximum size of a ferromagnetic nanocluster in a paramagnetic matrix. The <S> average size of a ferromagnetic cluster is ~100 nm (La-CMFCNO) and ~60 nm (LN-CMFCNO). The Smax maximum size is ~210 nm (La-CMFCNO) and ~205 nm (LN-CMFCNO). For Nd-CMFCNO, spin glass state (ferromagnetic cluster lower than 30 nm) was observed due to f-d exchange at low temperatures.
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Pareniuk, Dmytro. "Method of evaluation of the minimal sample size for acoustical signal therapy monitored via electroencephalographic activity of human brain." ScienceRise, no. 2 (April 30, 2021): 75–82. http://dx.doi.org/10.21303/2313-8416.2021.001736.
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The aim of the study. Improvement of the preparation to the acoustical signal therapy test or experiment of electroencephalographic activity of human brain and validation of the specified test results.
 The problem to be solved. Estimation of the minimal possible sample size for maintaining needed research accuracy in the research field of the electroencephalographic activity of human brain via monitoring of the brainwave patterns during exposure to the musical signal.
 Main scientific results. New method for selection minimal passable sample size for brainwave pattern studies is presented. Example of application of method for one rhythm of the brainwaves (delta-rhythm) is shown. Perspective way of obtaining clinically valuable differences between test group results was acquired. Differences between mean values for groups of results of different types of music and stress factor exposure are presented.
 The area of practical use of the research results. Research facilities dedicated to the study of electroencephalographic activity of human brain and medical facilities and institutions, dedicated to the treatment of pathologies of the central nervous system, brain damage, stress, and progressive post-stress action psychological state restoration.
 An innovative technological product. Dedicated method for quick estimation of minimal passable sample size for brainwave pattern studies, which is recommended for usage in the studies of the implementation of music therapy.
 The area of application of an innovative technological product. Electroencephalographic activity of human brain study via brainwave pattern research. Clinical practice of application of a music therapy.
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Quesada Carballo, Luís, María del Rosario Perez Perez, David Cantador Fernández, Alvaro Caballero Amores, and José María Fernández Rodríguez. "Optimum Particle Size of Treated Calcites for CO2 Capture in a Power Plant." Materials 12, no. 8 (2019): 1284. http://dx.doi.org/10.3390/ma12081284.
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This work has analyzed the influence of the particle size of a calcite from a quarry, whether original, calcined, or rehydrated, on the efficiency of CO2 capture of the gases emitted in a coal-fired power plant. Three different particle sizes 0.5 mm, 0.1 mm, and 0.045 mm have been studied. The calcination had a minimal effect on the particle size of the smaller samples A1045 and A1M1 (<30 μm). The N2 isotherms and the CO2 adsorption isotherms at 0 °C showed a very significant increase in the surface of the calcined and rehydrated samples (A15CH, A1045CH, and A1M1CH) with respect to the calcined or original samples. The results obtained showed that the capture of CO2 for the sample A1M1, with a smaller average particle size (<30 μm, is the most effective. For the sample A1M1 calcined and completely rehydrated (Ca(OH)2), the chemical adsorption of CO2 to form CaCO3 is practically total, under the experimental conditions used (550 °C and CO2 flow of 20 mL min−1). The weight increase was 34.11% and the adsorption capacity was 577.00 mg g−1. The experiment was repeated 10 times with the same sample A1M1 calcined and rehydrated. No appreciable loss of adsorption capacity was observed.
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Li, Hongran, Wanmei Qu, John J. Obrycki, et al. "Optimizing Sample Size for Population Genomic Study in a Global Invasive Lady Beetle, Harmonia Axyridis." Insects 11, no. 5 (2020): 290. http://dx.doi.org/10.3390/insects11050290.
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Finding optimal sample sizes is critical for the accurate estimation of genetic diversity of large invasive populations. Based on previous studies, we hypothesized that a minimal sample size of 3–8 individuals is sufficient to dissect the population architecture of the harlequin lady beetle, Harmonia axyridis, a biological control agent and an invasive alien species. Here, equipped with a type IIB endonuclease restriction site-associated (2b-RAD) DNA sequencing approach, we identified 13,766 and 13,929 single nucleotide polymorphisms (SNPs), respectively, among native and invasive H. axyridis populations. With this information we simulated populations using a randomly selected 3000 SNPs and a subset of individuals. From this simulation we finally determined that six individuals is the minimum sample size required for the accurate estimation of intra- and inter-population genetic diversity within and across H. axyridis populations. Our findings provide an empirical advantage for population genomic studies of H. axyridis in particular and suggest useful tactics for similar studies on multicellular organisms in general.
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van Smeden, Maarten, Karel GM Moons, Joris AH de Groot, et al. "Sample size for binary logistic prediction models: Beyond events per variable criteria." Statistical Methods in Medical Research 28, no. 8 (2018): 2455–74. http://dx.doi.org/10.1177/0962280218784726.
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Binary logistic regression is one of the most frequently applied statistical approaches for developing clinical prediction models. Developers of such models often rely on an Events Per Variable criterion (EPV), notably EPV ≥10, to determine the minimal sample size required and the maximum number of candidate predictors that can be examined. We present an extensive simulation study in which we studied the influence of EPV, events fraction, number of candidate predictors, the correlations and distributions of candidate predictor variables, area under the ROC curve, and predictor effects on out-of-sample predictive performance of prediction models. The out-of-sample performance (calibration, discrimination and probability prediction error) of developed prediction models was studied before and after regression shrinkage and variable selection. The results indicate that EPV does not have a strong relation with metrics of predictive performance, and is not an appropriate criterion for (binary) prediction model development studies. We show that out-of-sample predictive performance can better be approximated by considering the number of predictors, the total sample size and the events fraction. We propose that the development of new sample size criteria for prediction models should be based on these three parameters, and provide suggestions for improving sample size determination.
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Алиев Мехрали, Мирзали оглы, Зульфия Фаритовна Исмагилова, Наталия Николаевна Бурмистрова, and Екатерина Андреевна Созонтова. "Influence of rock sample size on anisotropy of strength properties." Нефтяная провинция, no. 2(30) (June 30, 2022): 88–97. http://dx.doi.org/10.25689/np.2022.2.88-97.
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В работе рассматриваются вопросы влияния основных размеров образцов горных пород, обладающих свойством изменчивости их прочности от направления, связанной с анизотропией. Такая работа выполняется обычно для изотропных пород, но также представляет интерес исследования в этой области, когда анизотропия прочностных свойств значительна. Для решения представленной задачи исходные данные заимствованы из работ других авторов. В одной из этих работ отношение высоты на диаметр изменяется в широких пределах. В дальнейшем был использован критерий разрушения, представляющий собой обобщение классического линейного критерия Кулона-Мора, с помощью которого определены прочностные сдвиговые свойства и угол внутреннего трения по разным направлениям, не проводя экспериментов. Также было выполнено решение задачи в условиях изменения бокового давления и по определению разрушающего давления в различных отношения бокового и разрушающего давлений. Расчеты показывают, что влияние размеров образца в большей степени оказывает случай, когда при различных боковых давлениях разрушающее давление ощутимо поперек или вдоль слоев. В промежуточных случаях в пределах от 30 до 60 это влияние минимально. Effect of dimensions of rock samples characterized by anisotropy-associated variations in strength vs. direction is discussed. Subjects of such studies are isotropic rocks, as a rule, however, when anisotropy of strength properties is high, findings of research can be of interest. For this study, input data from published literature were used. Some authors mention that aspect ratio changed over a wide range. Failure criterion, which is essentially a generalization of a classical Mohr-Coulomb linear criterion, was used to determine shear strength and angles of internal friction along various directions. No physical experiments were performed. The problem was solved for conditions of lateral thrust variations; failure pressure for different lateral thrust - failure pressure ratios was determined. Calculations show that the effect of dimensions of rock samples is mostly pronounced when failure pressure is notable across or along the layers at different lateral thrust. In the range of 30° to 60°, the effect is minimal.
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Zhang, Yong, Jing Qiu, Guanjun Liu, and Zhiao Zhao. "Fault Sample Generation for Virtual Testability Demonstration Test Subject to Minimal Maintenance and Scheduled Replacement." Mathematical Problems in Engineering 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/645047.
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Virtual testability demonstration test brings new requirements to the fault sample generation. First, fault occurrence process is described by stochastic process theory. It is discussed that fault occurrence process subject to minimal repair is nonhomogeneous Poisson process (NHPP). Second, the interarrival time distribution function of the next fault event is proposed and three typical kinds of parameterized NHPP are discussed. Third, the procedure of fault sample generation is put forward with the assumptions of minimal maintenance and scheduled replacement. The fault modes and their occurrence time subject to specified conditions and time period can be obtained. Finally, an antenna driving subsystem in automatic pointing and tracking platform is taken as a case to illustrate the proposed method. Results indicate that both the size and structure of the fault samples generated by the proposed method are reasonable and effective. The proposed method can be applied to virtual testability demonstration test well.
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C, Sunil Kumar, and Rama Sree R J. "Experiments Towards Determining Best Training Sample Size for Automated Evaluation of Descriptive Answers Through Sequential Minimal Optimization." ICTACT Journal on Soft Computing 4, no. 2 (2014): 710–14. http://dx.doi.org/10.21917/ijsc.2014.0102.
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Zhang, Wenfu, Shaohua Gu, Hong Chen, Cuicui Wang, Haitao Cheng, and Ge Wang. "Tensile properties and mechanism of laser-cut bamboo slivers." BioResources 14, no. 2 (2019): 4708–20. http://dx.doi.org/10.15376/biores.14.2.4708-4720.
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This study aimed to evaluate the tensile properties and the failure mechanisms of bamboo slivers that were subjected to different methods of laser-cutting with changing parameters. The failure of the sample was observed through in situ tensile testing combined with scanning electron microscopy. The results indicated that laser-cutting could achieve high efficiency and minimal size variation in machining; however, the calculated sample size needed modification. When the laser power, cutting rate, and sample size were equal to 40 W, 5 mm x s-1, and 2 mm, respectively, the achieved tensile strength was 328.8 MPa, and the tensile modulus was 25.2 GPa. During testing, the surface of the laser-cut sample exhibited brittle fractures (with its interior typically damaged between the basic tissue and the fiber interface), fiber breakage, and fiber extraction.
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Cui, Wanying, Zhongshan Yu, Jing Chang, et al. "Utilization of Ambient Ionization Mass Spectrometry in Forensic Toxicology Analysis." Advances in Analytic Science 2, no. 1 (2021): 10. http://dx.doi.org/10.54517/aas.v2i1.1983.
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<p class="MsoNormal" style="text-indent: 20.0pt; line-height: 15.0pt; mso-line-height-rule: exactly; mso-pagination: widow-orphan; layout-grid-mode: char; mso-layout-grid-align: none;"><span lang="EN-US" style="font-size: 10.0pt; mso-bidi-font-size: 11.0pt;">Ambient ionization mass spectrometry (AIMS) is a technique that allows for the analysis of target analytes in samples at atmospheric pressure with minimal or no sample preparation. Its advantages, including simplicity, speed, non-destructiveness, and broad applicability, make it highly useful in forensic toxicological analysis. This article provides an overview of the ambient ionization (AI) technique, categorizes samples into two types&mdash;in vivo and in vitro test materials&mdash;and summarizes AIMS applications in poison analysis across various sample types. It also explores future directions for AIMS in forensic toxicology.</span></p>
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Shvydka, S., V. Sarabeev, V. D. Estruch, and C. Cadarso-Suárez. "Optimum sample size to estimate mean parasite abundance in fish parasite surveys." Helminthologia 55, no. 1 (2018): 52–59. http://dx.doi.org/10.1515/helm-2017-0054.
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Summary To reach ethically and scientifically valid mean abundance values in parasitological and epidemiological studies this paper considers analytic and simulation approaches for sample size determination. The sample size estimation was carried out by applying mathematical formula with predetermined precision level and parameter of the negative binomial distribution estimated from the empirical data. A simulation approach to optimum sample size determination aimed at the estimation of true value of the mean abundance and its confidence interval (CI) was based on the Bag of Little Bootstraps (BLB). The abundance of two species of monogenean parasites Ligophorus cephali and L. mediterraneus from Mugil cephalus across the Azov-Black Seas localities were subjected to the analysis. The dispersion pattern of both helminth species could be characterized as a highly aggregated distribution with the variance being substantially larger than the mean abundance. The holistic approach applied here offers a wide range of appropriate methods in searching for the optimum sample size and the understanding about the expected precision level of the mean. Given the superior performance of the BLB relative to formulae with its few assumptions, the bootstrap procedure is the preferred method. Two important assessments were performed in the present study: i) based on CIs width a reasonable precision level for the mean abundance in parasitological surveys of Ligophorus spp. could be chosen between 0.8 and 0.5 with 1.6 and 1x mean of the CIs width, and ii) the sample size equal 80 or more host individuals allows accurate and precise estimation of mean abundance. Meanwhile for the host sample size in range between 25 and 40 individuals, the median estimates showed minimal bias but the sampling distribution skewed to the low values; a sample size of 10 host individuals yielded to unreliable estimates.
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Moerbeek, Mirjam. "Optimal allocations for two treatment comparisons within the proportional odds cumulative logits model." PLOS ONE 16, no. 4 (2021): e0250119. http://dx.doi.org/10.1371/journal.pone.0250119.
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This paper studies optimal treatment allocations for two treatment comparisons when the outcome is ordinal and analyzed by a proportional odds cumulative logits model. The variance of the treatment effect estimator is used as optimality criterion. The optimal design is sought so that this variance is minimal for a given total sample size or a given budget, meaning that the power for the test on treatment effect is maximal, or it is sought so that a required power level is achieved at a minimal total sample size or budget. Results are presented for three, five and seven ordered response categories, three treatment effect sizes and a skewed, bell-shaped or polarized distribution of the response probabilities. The optimal proportion subjects in the intervention condition decreases with the number of response categories and the costs for the intervention relative to those for the control. The relation between the optimal proportion and effect size depends on the distribution of the response probabilities. The widely used balanced design is not always the most efficient; its efficiency as compared to the optimal design decreases with increasing cost ratio. The optimal design is highly robust to misspecification of the response probabilities and treatment effect size. The optimal design methodology is illustrated using two pharmaceutical examples. A Shiny app is available to find the optimal treatment allocation, to evaluate the efficiency of the balanced design and to study the relation between budget or sample size and power.
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MANZATO, A. J., W. J. TADEI, and J. A. CORDEIRO. "Estimation of population profiles of two strains of the fly Megaselia scalaris (Diptera: Phoridae) by bootstrap simulation." Revista Brasileira de Biologia 60, no. 3 (2000): 415–24. http://dx.doi.org/10.1590/s0034-71082000000300006.
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Based on experimental population profiles of strains of the fly Megaselia scalaris (Phoridae), the minimal number of sample profiles was determined that should be repeated by bootstrap simulation process in order to obtain a confident estimation of the mean population profile and present estimations of the standard error as a precise measure of the simulations made. The original data are from experimental populations founded with SR and R4 strains, with three replicates, which were kept for 33 weeks by serial transfer technique in a constant temperature room (25 ± 1.0°C). The variable used was population size and the model adopted for each profile was a stationary stochastic process. By these simulations, the three experimental population profiles were enlarged so as to determine minimum sample size. After sample size was determined, bootstrap simulations were made in order to calculate confidence intervals and to compare the mean population profiles of these two strains. The results show that with a minimum sample size of 50, stabilization of means begins.
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Baležentis, Tomas, Aistė Galnaitytė, Irena Kriščiukaitienė, et al. "Decomposing Dynamics in the Farm Profitability: An Application of Index Decomposition Analysis to Lithuanian FADN Sample." Sustainability 11, no. 10 (2019): 2861. http://dx.doi.org/10.3390/su11102861.
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The changes in farm structure have been observed in Lithuania as well as in other Central and Eastern European countries. These changes, to a high extent, have been driven by decreasing profitability of the small farms. In this paper, we look into the changes in the profitability of Lithuanian family farms across different farm size groups. Farm size is measured in terms of the standard output. The period covered is 2005–2016. The index decomposition analysis model and Shapley value are adapted for the analysis. The proposed framework ensures complete decomposition among other desirable properties. The decomposition of the changes in profitability was carried out following the DuPont identity. The results suggest that for small (respectively large) farms the asset turnover (respectively profit margin) component appear more important, whereas the leverage effect remained minimal irrespectively of the farm size group.
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Yao, Keyu. "Parameters Estimates on Samples with Contamination." UNIVERSITY NEWS. NORTH-CAUCASIAN REGION. NATURAL SCIENCES SERIES, no. 1 (March 29, 2024): 56–62. http://dx.doi.org/10.18522/1026-2237-2024-1-56-62.
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Parametric estimates based on contaminated samples are considered in the paper. The paper provides an over-view of algorithms for estimating the mean and the variance for a one-dimensional sample, as well as estimating the mean vector and the covariance matrix for a multidimensional sample. The paper uses the Minimal Covariance Determinant (MCD) algorithm adapted for one-dimensional sample and the MCD algorithm for multidimensional sample. The parameters are estimated on a subsample, the size of which is determined by a given confidence probability. Examples for samples with different levels of contamination are considered. In both examples, the sample was a union of two subsamples. The first subsample, the main one, was generated by normal distribution laws. The second subsample, auxiliary, was generated by different distribution laws. The examples demonstrate the dependence of the estimation accuracy on the confidence level and contamination. The figures illustrate the operation of the MCD algorithm. The main idea of the paper is to show the robustness of the MCD algorithm.
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Silveira Neto, Luiz da, Giovanni Widmer, Valéria Marçal Felix de Lima, et al. "Prevalence of Cryptosporidium infection in domestic cats from an urban area in Brazil." Semina: Ciências Agrárias 41, no. 6 (2020): 2677–86. http://dx.doi.org/10.5433/1679-0359.2020v41n6p2677.
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We investigated the occurrence of Cryptosporidium oocysts shedding by domestic cats in an urban setting. The calculation of minimum sample size was based on an estimated prevalence of 10%, 5% absolute sampling error and a 5% significance level, resulting in 138 cats. A total of 612 owners of 2,290 cats had to be contacted for achieving the minimal sample size. In the end, only 55 owners accepted to participate in this investigation. Stool samples collected from 138 dogs were examined by microscopy using modified Kinyoun acid-fast staining, capture ELISA and nested-PCR followed by sequencing. Samples were considered positive when Cryptosporidium were detected by at least two diagnostic methods. Thirteen samples were positive (9.4%; 95% CI: 4.5 - 14.3). Cryptosporidium amplicons from seven out of the 13 samples were successfully sequenced and shared 99% genetic similarity to Cryptosporidium felis, GenBank access AF112575.1 was found. We concluded that Cryptosporidium infection is common in domestic cats from urban area and veterinary practitioners should guide cat owners to adopt preventive measures against the parasite to reduce the chance of infection in cats and householders.
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Overall, John E., and Robert S. Atlas. "Comparison of a Two-Stage and Three-Stage Interim-Analysis Procedure." Psychological Reports 71, no. 1 (1992): 3–14. http://dx.doi.org/10.2466/pr0.1992.71.1.3.
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A statistical model for combining p values from multiple tests of significance is used to define rejection and acceptance regions for two-stage and three-stage sampling plans. Type I error rates, power, frequencies of early termination decisions, and expected sample sizes are compared. Both the two-stage and three-stage procedures provide appropriate protection against Type I errors. The two-stage sampling plan with its single interim analysis entails minimal loss in power and provides substantial reduction in expected sample size as compared with a conventional single end-of-study test of significance for which power is in the adequate range. The three-stage sampling plan with its two interim analyses introduces somewhat greater reduction in power, but it compensates with greater reduction in expected sample size. Either interim-analysis strategy is more efficient than a single end-of-study analysis in terms of power per unit of sample size.
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Fu, Kang, Ying Xu, Jun Yang, and Wei Zhang. "System Availability Test Procedure with Minimum Operating Time." Advanced Materials Research 706-708 (June 2013): 2053–56. http://dx.doi.org/10.4028/www.scientific.net/amr.706-708.2053.
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In order to solve problem about how to test inherent availability of repairable system under minimum operating time and lognormal repair time, an inherent availability test procedure with fixed sample size is presented. The test procedure which is divided into alternate operating and repair process, should meet stated levels of producer’s risk and consumer’s risk. It is noticeable that minimal sample size and critical value calculation method research is considered as the key point of procedure design. At the end of this paper, course of a test procedure design and operation of inherent availability test and evaluation are described by example analysis.
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Strug, Ivona, Christopher Utzat, Amedeo Cappione, et al. "Development of a Univariate Membrane-Based Mid-Infrared Method for Protein Quantitation and Total Lipid Content Analysis of Biological Samples." Journal of Analytical Methods in Chemistry 2014 (2014): 1–12. http://dx.doi.org/10.1155/2014/657079.
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Biological samples present a range of complexities from homogeneous purified protein to multicomponent mixtures. Accurate qualification of such samples is paramount to downstream applications. We describe the development of an MIR spectroscopy-based analytical method offering simultaneous protein quantitation (0.25–5 mg/mL) and analysis of total lipid or detergent species, as well as the identification of other biomolecules present in biological samples. The method utilizes a hydrophilic PTFE membrane engineered for presentation of aqueous samples in a dried format compatible with fast infrared analysis. Unlike classical quantification techniques, the reported method is amino acid sequence independent and thus applicable to complex samples of unknown composition. By comparison to existing platforms, this MIR-based method enables direct quantification using minimal sample volume (2 µL); it is well-suited where repeat access and limited sample size are critical parameters. Further, accurate results can be derived without specialized training or knowledge of IR spectroscopy. Overall, the simplified application and analysis system provides a more cost-effective alternative to high-throughput IR systems for research laboratories with minimal throughput demands. In summary, the MIR-based system provides a viable alternative to current protein quantitation methods; it also uniquely offers simultaneous qualification of other components, notably lipids and detergents.
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Johnson, Abigail J., Alison Alvear, Dan Knights, Lisa S. Chow, and Anne E. Bantle. "A Randomized Pilot Study of Time-Restricted Eating Shows Minimal Microbiome Changes." Nutrients 17, no. 1 (2025): 185. https://doi.org/10.3390/nu17010185.
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Objective: TRE is an emerging approach in obesity treatment, yet there is limited data on how it influences gut microbiome composition in humans. Our objective was to characterize the gut microbiome of human participants before and after a TRE intervention. This is a secondary analysis of a previously published clinical trial examining the effects of time-restricted eating (TRE). Methods: In a previously published, 12-week randomized controlled trial, Chow et al. evaluated the effects of an 8-h TRE intervention on body composition in human participants. Chow et al. demonstrated significant reductions in weight, lean mass, and visceral fat in the TRE group compared to those following time-unrestricted eating (non-TRE). Stool samples were collected by a subset of those participants using home kits at both baseline and post-intervention for shotgun metagenomic sequencing for this secondary analysis. Microbiome community composition was compared before and after intervention as alpha and beta diversity. Results: Sixteen participants provided stool samples (eight in the TRE group and eight in the non-TRE group). Stool samples were collected from all participants at at least one time point, but both pre- and post-treatment samples were available from only five participants who completed both baseline and post-treatment collections. In alignment with the findings of Chow et al., the participants in the TRE group of the secondary analysis who collected microbiome sample(s) successfully reduced their eating window from an average of 15.3 ± 0.8 h at baseline to 9.3 ± 1.7 h during the intervention (mean ± SD, p < 0.001) and the non-TRE group’s eating window remained unchanged. While the TRE group lost weight and visceral fat mass, no effect of the TRE intervention was observed on alpha diversity (Shannon index, Simpson index, and number of taxa, linear mixed models), beta diversity (Bray–Curtis, PERMANOVA), even after controlling for weight and visceral fat changes. Conclusions: Our analysis did not detect any significant differences in gut microbiome composition or diversity indices between participants undergoing a TRE intervention and those in the control group. The study’s findings are limited by a small sample size, short duration, and the collection of stool samples at only two time points. Future studies with larger sample sizes, longer durations, and more frequent sampling, and collection of detailed dietary data are needed to better understand the relationship between TRE and gut microbiome dynamics.
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Kommel, Lembit A., V. Mikli, R. Traksmaa, et al. "Influence of the SPD Processing Features on the Nanostructure and Properties of a Pure Niobium." Materials Science Forum 667-669 (December 2010): 785–90. http://dx.doi.org/10.4028/www.scientific.net/msf.667-669.785.
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The structurization of a high purity niobium from double electron-beam melted cast microstructure to fine-grained microstructure was completed by equal-channel angular pressing by the Bc route up to a Von Mieses strain of 13.8. In addition, for the viscoplastic behavior study as well as nanostructure and properties improving the hard cyclic viscoplastic deformation, die forging at room temperature and followed heat treatment with low heating rate were conducted. The nanostructure of processed samples was characterized by transmission electron microscopy and X-ray diffraction testing. This paper focuses on several new trends in the study of improved mechanical and physical properties of pure niobium, to what purpose these materials will be used in industry. The crystallite size, microstrains and dislocation density in severe plastic deformed pure niobium were calculated and electric conduction was measured. The nanocrystalline microstructure with minimal crystallite size down to 62 nm as mean in cross-section of sample was received. By this the dislocation density varies from 5.0 E+10 to 2.0 E+11 cm-2 and was maximal for pure niobium which has minimal electrical conductivity, maximal value of hkl-parameter and maximal relative microstresses. The microhardness was maximal for sample after 12 passes by Bc route and for samples with 8 and 10 passes followed heat treatment at 170 and 350°C. The mechanisms answerable for the electronic conduction were discussed according to the microstructure evolution in the different directions and for different strain levels.
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Kushadiwijaya, Mikhail, Putu Astawa, I. Gede Eka Wiratnaya, and Komang Septian Sandiwidayat. "Open versus Minimal Invasive Curettage in Simple Bone Cyst: A Systematic Review." International Journal of Research and Review 12, no. 3 (2025): 239–50. https://doi.org/10.52403/ijrr.20250331.
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Introduction: Open curettage is the standard surgical procedure for simple bone cyst. However, this procedure has some disadvantages so that minimal invasive curettage becomes one of the treatment alternatives. Method: A systematic search was conducted through PubMed, Google Scholar, and Cochrane Library. Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria were used. Result: A total of three studies were included. Total sample size ranged from 16-40 patients, aged ranged from 4-28 years, and 64 males and 18 females were examined. Discussion: Open curettage was inferior to minimal invasive curettage in terms of mean hospital stay (4,7 vs 2,2 days, p < 0,01), time to full weight bearing (17,0 vs 4,0 days, p < 0,01), time to return to sport activities (14,5 vs 6,5 weeks, p < 0,01), time to solid union (6,6 - 12,2 vs 3,7 months, p < 0,05), AOFAS scale (96,1 vs 97,5, p > 0,05), time to complete radiological healing (12,8 vs 14,6 weeks, p > 0,05), Chang’s radiological evaluation (14/19 vs 11/12 healed, p > 0,05), and number of complications (1 sural neuritis, 1 CPC leakage vs 0 complication, p > 0,05). However, mean operating time was found to be inconsistent between studies and mean number of procedures and recurrence were relatively same in both groups. Conclusion: This study report that minimal invasive curettage is superior to open curettage. Further study with higher amount of included studies and sample size is needed. Keywords: open curettage, minimal invasive curettage, simple bone cyst
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Žunkovič, Breda, Nataša Kejžar, and Fajko F. Bajrović. "Standard Heart Rate Variability Parameters—Their Within-Session Stability, Reliability, and Sample Size Required to Detect the Minimal Clinically Important Effect." Journal of Clinical Medicine 12, no. 9 (2023): 3118. http://dx.doi.org/10.3390/jcm12093118.
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Many intervention studies assume the stability of heart rate variability (HRV) parameters, and their sample sizes are often small, which can significantly affect their conclusions. The aim of this study is to assess the stability and reliability of standard HRV parameters within a single resting session, and to estimate the sample size required to detect the minimal clinically important effect of an intervention. Heart rate was recorded in 50 adult healthy subjects for 50 min in a seated position. Eight standard HRV parameters were calculated from five evenly spaced 5 min intervals. Stability was assessed by comparing the mean values of HRV parameters between the consecutive five test–retest measurements. Absolute reliability was determined by standard error of measurement, and relative reliability by intraclass correlation coefficient. The sample size required to detect a mean difference of ≥30% of between-subject standard deviation was estimated. As expected, almost all HRV parameters had poor absolute reliability but most HRV parameters had substantial to excellent relative reliability. We found statistically significant differences in almost all HRV parameters between the first 20 min and the last 30 min of the session. The estimated sample size ranged from 19 to 300 subjects for the first 20 min and from 36 to 194 subjects for the last 30 min of the session, depending on the selected HRV parameter. We concluded that optimal HRV measurement protocols in a resting seated position should be performed within the first 20 min or between 20 and 50 min after assuming a resting seated position. Future interventional HRV studies should include a sufficient number of subjects and consider the Bonferroni correction according to the number of selected HRV parameters to achieve an appropriate level of study power and precision.
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Sysoev, E. I., M. M. Sychov, L. N. Shafigullin, and S. V. Dyachenko. "Design of Sound Absorbing Honeycomb Materials with Geometry of Triply Periodic Minimal Surfaces (TPMS)." Akustičeskij žurnal 70, no. 5 (2024): 765–77. https://doi.org/10.31857/s0320791924050111.
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The use of cellular materials with the geometry of triply periodic minimum energy surfaces (TPMES) is proposed for the creation of durable cellular materials with controlled acoustic characteristics. Homogeneous unit cells with the Primitive, Diamond, FRD and Gyroid topologies of different porosity were developed and their acoustic parameters were determined. Using the semi-phenomenological Johnson-Champoux-Allard-Lafarge-Pride model, the sound absorption capacity of materials with this geometry was estimated. It was shown that by varying the size of the unit cell and the thickness of the sample, it is possible to control the acoustic characteristics and the average sound absorption coefficient in the range from 0.2 to 0.8. The reliability of the calculations was confirmed experimentally using additively manufactured samples. The results demonstrate the potential of using TPMES for creating materials with controlled pore geometry to achieve predictable sound absorption characteristics.
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Weiss, Iris, Birgit Vogel-Heuser, Emanuel Trunzer, and Simon Kruppa. "Product Quality Monitoring in Hydraulic Presses Using a Minimal Sample of Sensor and Actuator Data." ACM Transactions on Internet Technology 21, no. 2 (2021): 1–23. http://dx.doi.org/10.1145/3436238.
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Machine learning and artificial intelligence provide methods and algorithms to take advantage of sensor and actuator data in automated production systems. Product quality monitoring is one of the promising applications available for data-driven modeling, particularly in cases where the quality parameters cannot be measured with reasonable effort. This is the case for defects such as cracks in workpieces of hydraulic metal powder presses. However, the variety of shapes produced at a powder press requires training of individual models based on a minimal sample size of unlabeled data to adapt to changing settings. Therefore, this article proposes an unsupervised product quality monitoring approach based on dynamic time warping and non-linear regression to detect anomalies in unlabeled sensor and actuator data. A preprocessing step that isolates only the relevant intervals of the process is further introduced, facilitating efficient product quality monitoring. The evaluation on an industrial dataset with 37 samples, generated in test runs, shows a true-positive rate for detected product quality defects of 100% while preserving an acceptable accuracy. Moreover, the approach achieves the output within less than 10 seconds, assuring that the result is available before the next workpiece is processed. In this way, efficient product quality management is possible, reducing time- and cost-intensive quality inspections.
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Morley, Alexander A., Sue Latham, Michael J. Brisco, Pamela J. Sykes, Bryone Kuss, and Keith Waters. "Improved Measurement of Minimal Residual Disease (MRD)." Blood 108, no. 11 (2006): 2284. http://dx.doi.org/10.1182/blood.v108.11.2284.2284.
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Abstract A new and improved method for measurement of minimal residual disease (MRD) was developed. Method the total repertoire of leukaemic rearrangements of the immunoglobulin heavy chain (IgH) gene.was determined by performing multiple parallel Q-PCRs in microplates to determine usage of individual V and J segments. This enabled detection and quantification of clones ranging in size from 100% to approximately 0.03% of the leukemic population. MRD measurement involved nested Q-PCR using the specific V and J primers and internal primers based on the sequence of the rearrangement of interest. Following informed parental consent, 25 children with B-ALL were studied at the end of induction therapy. Under general anesthesia, 4 aspirations, 2 from each iliac spine, were performed and on each sample MRD was measured on 2 different days. This enabled definition of the laboratory and sampling factors important in measurement of MRD. Results Repertoire analysis was very effective in identifying rearrangements of the IgH gene suitable for use as molecular markers, being superior to the commonly-used BIOMED-2 protocol for identification of both large and small clones. Two or more rearrangements marking large clones were detected in 20 of the 25 patients. The median MRD level at the end of induction was 2.1 x 10−5. A level of > 10−3 was seen in 4 patients and < 10−7 in 4. Sensitivity of detection in a single sample was approximately 2 x 10−6, which is 1–2 orders of magnitude better than current techniques. Figure Figure The SD of measurement depended on the number of target rearrangements present in the sample, reflecting the Poisson statistical uncertainty inherent in measurement of small numbers of events. For > 50 rearrangements SD was 0.23 log units, but below this level the SD rose steeply. 50 targets in 1 μg of DNA corresponds to an MRD of approximately 3 x 10−4. Figure Figure There was significant sampling error. In 1 patient there was 1000-fold MRD difference between the 2 iliac spines. Conclusions We recommend that, for MRD measurement, -an aspiration should be performed from each iliac spine, with each sample being quantified separately and an average obtained -each measurement should involve at least 10 μg of good-quality DNA The MRD value so obtained should have sufficient accuracy, sensitivity and precision for clinical decisions based upon the value to be made with confidence. The described methods for MRD measurement should also be applicable to monitoring of all B-lymphocyte neoplasms, in addition to ALL.
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Cheng, Mao, Zachariah Wargel, Duarte Magalhaes, and Richard Axelbaum. "A Novel Optical Instrument for On-Line Measurement of Particle Size Distribution—Application to Clean Coal Technologies." Energies 18, no. 3 (2025): 720. https://doi.org/10.3390/en18030720.
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A flow cell is a critical measurement interface for many optical instruments. However, the flows are often sampled under harsh conditions, such as under high pressure and/or high temperature, in the presence of particles, moisture, vapors with high dew points or corrosive gases. Therefore, obtaining a high-optical-quality flow cell that does not perturb the measurement is a significant challenge. To address this challenge, we proposed a new flow cell that employs a unique laminar coaxial flow field (for the purge and sample flows). A test system was built to conduct particle size distribution (PSD) measurements with no sampling bias using a state-of-the-art analyzer (Malvern Panalytical Insitec). The results revealed that the measurement zone is well defined solely by the sample flow, and the optical windows are well protected by the purge flow, with minimal risk of any depositions from the sample flow. Using this flow cell, the Insitec can successfully measure PSD under high pressure and temperature under moist, corrosive conditions without generating any sampling bias. Importantly, we successfully applied this flow cell for on-line PSD measurement for the flue gas of a 100 kWth pressurized oxy-coal combustor operating at 15 bara.
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Goyal, Mayank, Rosalie McDonough, Marc Fisher, and Johanna Ospel. "The Challenge of Designing Stroke Trials That Change Practice: MCID vs. Sample Size and Pragmatism." Journal of Stroke 24, no. 1 (2022): 49–56. http://dx.doi.org/10.5853/jos.2021.02740.
Full textAbstract:
Randomized controlled trials (RCT) are the basis for evidence-based acute stroke care. For an RCT to change practice, its results have to be statistically significant and clinically meaningful. While methods to assess statistical significance are standardized and widely agreed upon, there is no clear consensus on how to assess clinical significance. Researchers often refer to the minimal clinically important difference (MCID) when describing the smallest change in outcomes that is considered meaningful to patients and leads to a change in patient management. It is widely accepted that a treatment should only be adopted when its effect on outcome is equal to or larger than the MCID. There are however situations in which it is reasonable to decide against adopting a treatment, even when its beneficial effect matches or exceeds the MCID, for example when it is resource- intensive and associated with high costs. Furthermore, while the MCID represents an important concept in this regard, defining it for an individual trial is difficult as it is highly context specific. In the following, we use hypothetical stroke trial examples to review the challenges related to MCID, sample size and pragmatic considerations that researchers face in acute stroke trials, and propose a framework for designing meaningful stroke trials that have the potential to change clinical practice.
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Joo, Soo Bin, Gun Woo No, Young Hoon Jung, Min Jae Baek, Dong Jun Lee, and Jung Gi Kim. "Scan Strategy Effect on the Mechanical Properties and Microstructure of Directed Energy Deposited 18Ni300 Maraging Steel." Korean Journal of Metals and Materials 63, no. 1 (2025): 1–10. https://doi.org/10.3365/kjmm.2025.63.1.1.
Full textAbstract:
Although the laser scan strategy does not affect the energy density of laser-based additive manufacturing, changes in laser scan direction critically influence the residual stress and microstructure of metallic components. However, only a limited number of studies have investigated the role of laser scan strategy on the microstructure and mechanical properties of additively manufactured maraging steels. Therefore, this study examines the effect of laser scan strategy on the mechanical properties of 18Ni300 maraging steel. Different laser scan strategies influence the morphologies of the molten pool, where retained austenite is concentrated in 18Ni300 maraging steel. The 45o sample exhibits a denser molten pool distribution compared to the other samples due to reduced layer overlapping. Because of the plastic strain incompatibility between martensite and austenite at the molten pool boundary, this dense molten pool distribution in the 45o sample resulted in the highest back-stress hardening. Additionally, the minimal layer overlapping in the 45o sample reduces heat exposure during laser-based additive manufacturing, leading to a finer martensite block and lath size. By combining high back-stress hardening with a fine martensite block and lath size, the 45o sample achieved the highest tensile property compared to the other samples. These results indicate that the selection of laser scan strategy is crucial for designing a heterogeneous microstructure in additively manufactured parts, which can enhance mechanical properties, even with the same energy density.