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Journal articles on the topic 'Trait estimation'

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1

Fanourakis, Dimitrios, Filippos Kazakos, and Panayiotis A. Nektarios. "Allometric Individual Leaf Area Estimation in Chrysanthemum." Agronomy 11, no. 4 (2021): 795. http://dx.doi.org/10.3390/agronomy11040795.

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A model for estimating the area of individual leaves (LA) by employing their dimensions was developed for chrysanthemum. Further hypotheses were tested: (a) LA estimation is improved by considering blade length (Lb) rather than leaf length (L), and (b) a reasonable LA estimation can be attainable by considering L in conjunction to a shape trait, which is cultivar dependent. For the model development, six cultivars were employed (1500 leaves in total), while for model validation, an independent set of nine cultivars was utilized (1125 leaves in total). Several characteristics were digitally ass
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2

Cappa, Eduardo P., and Rodolfo JC Cantet. "Bayesian inference for normal multiple-trait individual-tree models with missing records via full conjugate Gibbs." Canadian Journal of Forest Research 36, no. 5 (2006): 1276–85. http://dx.doi.org/10.1139/x06-024.

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In forest genetics, restricted maximum likelihood (REML) estimation of (co)variance components from normal multiple-trait individual-tree models is affected by the absence of observations in any trait and individual. Missing records affect the form of the distribution of REML estimates of genetics parameters, or of functions of them, and the estimating equations are computationally involved when several traits are analysed. An alternative to REML estimation is a fully Bayesian approach through Markov chain Monte Carlo. The present research describes the use of the full conjugate Gibbs algorith
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3

Zhu, Anqi, Nana Matoba, Emma P. Wilson, et al. "MRLocus: Identifying causal genes mediating a trait through Bayesian estimation of allelic heterogeneity." PLOS Genetics 17, no. 4 (2021): e1009455. http://dx.doi.org/10.1371/journal.pgen.1009455.

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Expression quantitative trait loci (eQTL) studies are used to understand the regulatory function of non-coding genome-wide association study (GWAS) risk loci, but colocalization alone does not demonstrate a causal relationship of gene expression affecting a trait. Evidence for mediation, that perturbation of gene expression in a given tissue or developmental context will induce a change in the downstream GWAS trait, can be provided by two-sample Mendelian Randomization (MR). Here, we introduce a new statistical method, MRLocus, for Bayesian estimation of the gene-to-trait effect from eQTL and
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4

Thomas, Neal. "Assessing Model Sensitivity of the Imputation Methods Used in the National Assessment of Educational Progress." Journal of Educational and Behavioral Statistics 25, no. 4 (2000): 351–71. http://dx.doi.org/10.3102/10769986025004351.

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The National Assessment of Educational Progress (NAEP) uses latent trait item response models to summarize performance of students on assessments of educational proficiency in different subject areas such as mathematics and reading. Because of limited examination time and concerns about student motivation. NAEP employs sparse matrix sampling designs that assign a small number of examination items to each sampled student to measure broad curriculums. As a consequence, each sampled student’s latent trait is not accurately measured, and NAEP uses multiple imputation missing data statistical metho
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Lopez, Bryan Irvine, Ju-Hwan Son, Kangseok Seo, and Dajeong Lim. "Estimation of Genetic Parameters for Reproductive Traits in Hanwoo (Korean Cattle)." Animals 9, no. 10 (2019): 715. http://dx.doi.org/10.3390/ani9100715.

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Genetic parameters for the reproductive traits of Hanwoo cattle were estimated using data obtained from 15,355 cows in 92 herds across South Korea, which were inseminated from May 1997 to July 2016. An “average information” restricted maximum likelihood (REML) procedure that fit in single-trait and multi-trait animal models was used to estimate the variance components of age at first calving (AFC), calving interval (CI), days open (DO), and gestation length (GL). Results showed the low estimates of heritability for all reproductive traits from both single-trait and multi-trait models. Estimate
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6

McINTYRE, LAUREN M., CYNTHIA J. COFFMAN, and R. W. DOERGE. "Detection and localization of a single binary trait locus in experimental populations." Genetical Research 78, no. 1 (2001): 79–92. http://dx.doi.org/10.1017/s0016672301005092.

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The advancements made in molecular technology coupled with statistical methodology have led to the successful detection and location of genomic regions (quantitative trait loci; QTL) associated with quantitative traits. Binary traits (e.g. susceptibility/resistance), while not quantitative in nature, are equally important for the purpose of detecting and locating significant associations with genomic regions. Existing interval regression methods used in binary trait analysis are adapted from quantitative trait analysis and the tests for regression coefficients are tests of effect, not detectio
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7

Nagy, I., J. Farkas, I. Curik, G. Gorjanc, P. Gyovai, and Zs Szendrő. "Estimation of additive and dominance variance for litter size components in rabbits." Czech Journal of Animal Science 59, No. 4 (2014): 182–89. http://dx.doi.org/10.17221/7342-cjas.

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Additive, dominance, and permanent environmental variance components were estimated for the number of kits born alive, number of kits born dead, and total number of kits born of a synthetic rabbit line (called Pannon Ka). The data file consisted of 11 582 kindling records of 2620 does collected between the years 1996–2013. The total number of animals in the pedigree files was 4012. The examined traits were evaluated using single-trait and two-trait (number of kits born alive-dead) animal models containing all or part of the following effects: additive genetic effects, permanent envir
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8

Gao, Boran, Can Yang, Jin Liu, and Xiang Zhou. "Accurate genetic and environmental covariance estimation with composite likelihood in genome-wide association studies." PLOS Genetics 17, no. 1 (2021): e1009293. http://dx.doi.org/10.1371/journal.pgen.1009293.

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Genetic and environmental covariances between pairs of complex traits are important quantitative measurements that characterize their shared genetic and environmental architectures. Accurate estimation of genetic and environmental covariances in genome-wide association studies (GWASs) can help us identify common genetic and environmental factors associated with both traits and facilitate the investigation of their causal relationship. Genetic and environmental covariances are often modeled through multivariate linear mixed models. Existing algorithms for covariance estimation include the tradi
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9

Song, Huan, Chenghui Tan, Chuanlin Zhu, Dianzhi Liu, and Wenbo Peng. "The Influence of Emotion Regulation on Estimation Strategy Execution in Individuals with Trait Anxiety." Brain Sciences 12, no. 9 (2022): 1204. http://dx.doi.org/10.3390/brainsci12091204.

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Previous studies have shown that some negative emotions hinder estimation strategy execution. However, these studies rarely investigate the influence of negative emotions on the estimation strategy execution in individuals with trait anxiety. The present study examines the relationship between negative emotions and trait anxiety in individuals’ estimation strategy execution. Moreover, it looks into the influence of different emotion regulation strategies on their estimation strategy execution. In October 2010, 803 college students were evaluated using the Trait Anxiety Scale. From these partic
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10

Krupová, Zuzana, Emil Krupa, Ludmila Zavadilová, Eva Kašná, and Eliska Žáková. "Current challenges for trait economic values in animal breeding." Czech Journal of Animal Science 65, No. 12 (2020): 454–62. http://dx.doi.org/10.17221/161/2020-cjas.

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Modern selection approaches are expected to bring about the cumulative and permanent improvement of animal performance and profitability of animal production. Breeding values of traits along with trait economic values (EVs) are utilised for economic selection purposes with many species all over the world. Currently, some challenges related to trait EVs in animal breeding should be considered. First, the selection response based on the higher accuracy of genomic selection may be reduced due to improper weighting of the trait breeding values of selection candidates. A comprehensive approach appl
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11

Ronin, Yefim I., Abraham B. Korol, and Eviatar Nevo. "Single- and Multiple-Trait Mapping Analysis of Linked Quantitative Trait Loci: Some Asymptotic Analytical Approximations." Genetics 151, no. 1 (1999): 387–96. http://dx.doi.org/10.1093/genetics/151.1.387.

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Abstract Estimating the resolution power of mapping analysis of linked quantitative trait loci (QTL) remains a difficult problem, which has been previously addressed mainly by Monte Carlo simulations. The analytical method of evaluation of the expected LOD developed in this article spreads the “deterministic sampling approach for the case of two linked QTL for single- and two-trait analysis. Several complicated questions are addressed through this evaluation: the dependence of QTL detection power on the QTL effects, residual correlation between the traits, and the effect of epistatic interacti
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12

Marcondes, Rafael S. "Realistic scenarios of missing taxa in phylogenetic comparative methods and their effects on model selection and parameter estimation." PeerJ 7 (October 11, 2019): e7917. http://dx.doi.org/10.7717/peerj.7917.

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Model-based analyses of continuous trait evolution enable rich evolutionary insight. These analyses require a phylogenetic tree and a vector of trait values for the tree’s terminal taxa, but rarely do a tree and dataset include all taxa within a clade. Because the probability that a taxon is included in a dataset depends on ecological traits that have phylogenetic signal, missing taxa in real datasets should be expected to be phylogenetically clumped or correlated to the modelled trait. I examined whether those types of missing taxa represent a problem for model selection and parameter estimat
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13

Feuerstahler, Leah M. "Sources of Error in IRT Trait Estimation." Applied Psychological Measurement 42, no. 5 (2017): 359–75. http://dx.doi.org/10.1177/0146621617733955.

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In item response theory (IRT), item response probabilities are a function of item characteristics and latent trait scores. Within an IRT framework, trait score misestimation results from (a) random error, (b) the trait score estimation method, (c) errors in item parameter estimation, and (d) model misspecification. This study investigated the relative effects of these error sources on the bias and confidence interval coverage rates for trait scores. Our results showed that overall, bias values were close to 0, and coverage rates were fairly accurate for central trait scores and trait estimatio
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14

NAGAI, J., C. Y. LIN, and A. J. McALLISTER. "SIMULTANEOUS ESTIMATION OF GENETIC PARAMETERS OF LIFETIME REPRODUCTIVE TRAITS IN MICE." Canadian Journal of Animal Science 68, no. 4 (1988): 1291–95. http://dx.doi.org/10.4141/cjas88-145.

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Heritabilities and correlations between the length of reproductive life and number of parturitions during lifetime in mice were estimated from bivariate full-sib mixed-model analysis. Heritability estimates from sire components were low (0.01) for the two traits and those from dam components were slightly higher (0.06 and 0.05). Estimates of genetic and phenotypic correlations ranged from 0.89 to 0.99. It was concluded that the two traits are virtually the same trait biologically. Implication of these results for selection of lifetime production in mice and dairy cattle is discussed. Key words
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15

Srivastava, Swati, Bryan Irvine Lopez, Sara de las Heras-Saldana, et al. "Estimation of Genetic Parameters by Single-Trait and Multi-Trait Models for Carcass Traits in Hanwoo Cattle." Animals 9, no. 12 (2019): 1061. http://dx.doi.org/10.3390/ani9121061.

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Hanwoo breed is preferred in South Korea because of the high standards in marbling and the palatability of its meat. Numerous studies have been conducted and are ongoing to increase the meat production and quality in this beef population. The aim of this study was to estimate and compare genetic parameters for carcass traits using BLUPF90 software. Four models were constructed, single trait pedigree model (STPM), single-trait genomic model (STGM), multi-trait pedigree model (MTPM), and multi-trait genomic model (MTGM), using the pedigree, phenotype, and genomic information of 7991 Hanwoo cattl
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16

Bürkner, Paul-Christian, Niklas Schulte, and Heinz Holling. "On the Statistical and Practical Limitations of Thurstonian IRT Models." Educational and Psychological Measurement 79, no. 5 (2019): 827–54. http://dx.doi.org/10.1177/0013164419832063.

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Forced-choice questionnaires have been proposed to avoid common response biases typically associated with rating scale questionnaires. To overcome ipsativity issues of trait scores obtained from classical scoring approaches of forced-choice items, advanced methods from item response theory (IRT) such as the Thurstonian IRT model have been proposed. For convenient model specification, we introduce the thurstonianIRT R package, which uses Mplus, lavaan, and Stan for model estimation. Based on practical considerations, we establish that items within one block need to be equally keyed to achieve s
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17

Song, Jie, Yiqing Zou, Yuchang Wu, et al. "Decomposing heritability and genetic covariance by direct and indirect effect paths." PLOS Genetics 19, no. 1 (2023): e1010620. http://dx.doi.org/10.1371/journal.pgen.1010620.

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Estimation of heritability and genetic covariance is crucial for quantifying and understanding complex trait genetic architecture and is employed in almost all recent genome-wide association studies (GWAS). However, many existing approaches for heritability estimation and almost all methods for estimating genetic correlation ignore the presence of indirect genetic effects, i.e., genotype-phenotype associations confounded by the parental genome and family environment, and may thus lead to incorrect interpretation especially for human sociobehavioral phenotypes. In this work, we introduce a stat
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18

Konigsberg, Lyle W., Susan R. Frankenberg, and Helen M. Liversidge. "Optimal trait scoring for age estimation." American Journal of Physical Anthropology 159, no. 4 (2015): 557–76. http://dx.doi.org/10.1002/ajpa.22914.

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19

Wang, Peiyao, Zhaotong Lin, Haoran Xue, and Wei Pan. "Collider bias correction for multiple covariates in GWAS using robust multivariable Mendelian randomization." PLOS Genetics 20, no. 4 (2024): e1011246. http://dx.doi.org/10.1371/journal.pgen.1011246.

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Genome-wide association studies (GWAS) have identified many genetic loci associated with complex traits and diseases in the past 20 years. Multiple heritable covariates may be added into GWAS regression models to estimate direct effects of genetic variants on a focal trait, or to improve the power by accounting for environmental effects and other sources of trait variations. When one or more covariates are causally affected by both genetic variants and hidden confounders, adjusting for them in GWAS will produce biased estimation of SNP effects, known as collider bias. Several approaches have b
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20

Novotna, Alexandra, Alena Birovas, Hana Vostra-Vydrova, Zdenka Vesela, and Lubos Vostry. "Genetic Parameters of Performance and Conformation Traits of 3-Year-Old Warmblood Sport Horses in the Czech Republic." Animals 12, no. 21 (2022): 2957. http://dx.doi.org/10.3390/ani12212957.

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The aim of this study was to estimate the genetic parameters of a one-day performance test together with the linear type traits of 3-year-old warmblood horses. The study of genetic parameters was based on 5958 tested horses in the period 1998–2021. A total of 22 traits of linear description, three quantitatively measured traits, and one summary mark from the performance test were tested. The model equation included the fixed effect of gender and combination effects of classifier–year of evaluation–place. A single-trait animal model was used for the estimation of heritability and genetic varian
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21

Deinzer, Renate, Rolf Steyer, Michael Eid, et al. "Situational effects in trait assessment: The FPI, NEOFFI, and EPI questionnaires." European Journal of Personality 9, no. 1 (1995): 1–23. http://dx.doi.org/10.1002/per.2410090102.

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While most researchers do agree now that situations may have an effect in the assessment of traits, the consequences have been neglected, so far: if situations affect the assessment of traits we have to take this fact into account in studies on reliability and validity of measurement instruments and their application. In the theoretical part of this article we provide a more formal exposition of this point, introducing the basic concepts of latent state–trait (LST) theory. LST theory and the associated models allow for the estimation of the situational impact on trait measures in non‐experimen
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22

Glas, C. A. W. "The Rasch Model and Multistage Testing." Journal of Educational Statistics 13, no. 1 (1988): 45–52. http://dx.doi.org/10.3102/10769986013001045.

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This paper concerns the problem of estimating the item parameters of latent trait models in a multistage testing design. It is shown that using the Rasch model and conditional maximum likelihood estimates does not lead to solvable estimation equations. It is also shown that marginal maximum likelihood estimation, which assumes a sample of subjects from a population with a specified distribution of ability, will lead to solvable estimation equations, both in the Rasch model and in the Birnbaum model.
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23

Brzáková, Michaela, Ludmila Zavadilová, Josef Přibyl, Petr Pešek, Eva Kašná, and Anita Kranjčevičová. "Estimation of genetic parameters for female fertility traits in the Czech Holstein population." Czech Journal of Animal Science 64, No. 5 (2019): 199–206. http://dx.doi.org/10.17221/51/2018-cjas.

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Genetic parameters for fertility traits in Czech Holstein population were estimated. The database obtained from the Czech-Moravian Breeders Corporation with 6 414 486 insemination records between years 2005–2015 was used. Date of calving of the selected animals was taken from the database of milk records from 2005–2015. Fertility traits were age at first service (AFS), age at first calving (AFC), days open (DO), calving interval (CI) and first service to conception interval in cows (FSC-C) and heifers (FSC-H). The heritability of each trait was estimated using single-trait animal models. The m
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Leite, Mauro Sergio de Oliveira, Luiz Alexandre Peternelli, Márcio Henrique Pereira Barbosa, Paulo Roberto Cecon, and Cosme Damião Cruz. "Sample size for full-sib family evaluation in sugarcane." Pesquisa Agropecuária Brasileira 44, no. 12 (2009): 1562–74. http://dx.doi.org/10.1590/s0100-204x2009001200002.

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The objective of this study was to determine the minimum number of plants per plot that must be sampled in experiments with sugarcane (Saccharum officinarum) full-sib families in order to provide an effective estimation of genetic and phenotypic parameters of yield-related traits. The data were collected in a randomized complete block design with 18 sugarcane full-sib families and 6 replicates, with 20 plants per plot. The sample size was determined using resampling techniques with replacement, followed by an estimation of genetic and phenotypic parameters. Sample-size estimates varied accordi
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25

Luo, Z. W., and Chung-I. Wu. "Modeling Linkage Disequilibrium Between a Polymorphic Marker Locus and a Locus Affecting Complex Dichotomous Traits in Natural Populations." Genetics 158, no. 4 (2001): 1785–800. http://dx.doi.org/10.1093/genetics/158.4.1785.

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AbstractLinkage disequilibrium is an important topic in evolutionary and population genetics. An issue yet to be settled is the theory required to extend the linkage disequilibrium analysis to complex traits. In this study, we present theoretical analysis and methods for detecting or estimating linkage disequilibrium (LD) between a polymorphic marker locus and any one of the loci affecting a complex dichotomous trait on the basis of samples randomly or selectively collected from natural populations. Statistical properties of these methods were investigated and their powers were compared analyt
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26

Johnson, Ruth, Kathryn S. Burch, Kangcheng Hou, Mario Paciuc, Bogdan Pasaniuc, and Sriram Sankararaman. "Estimation of regional polygenicity from GWAS provides insights into the genetic architecture of complex traits." PLOS Computational Biology 17, no. 10 (2021): e1009483. http://dx.doi.org/10.1371/journal.pcbi.1009483.

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The number of variants that have a non-zero effect on a trait (i.e. polygenicity) is a fundamental parameter in the study of the genetic architecture of a complex trait. Although many previous studies have investigated polygenicity at a genome-wide scale, a detailed understanding of how polygenicity varies across genomic regions is currently lacking. In this work, we propose an accurate and scalable statistical framework to estimate regional polygenicity for a complex trait. We show that our approach yields approximately unbiased estimates of regional polygenicity in simulations across a wide-
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27

Song, Huan, Chenghui Tan, Chuanlin Zhu, Dianzhi Liu, and Wenbo Peng. "Creative Cognitive Reappraisal Promotes Estimation Strategy Execution in Individuals with Trait Anxiety." Brain Sciences 15, no. 4 (2025): 378. https://doi.org/10.3390/brainsci15040378.

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Objectives: This study aimed to investigate the impact of the creative cognitive reappraisal on the estimation strategies execution in college students with trait anxiety. Methods: Using the Trait Anxiety Scale, 47 participants with high (HTA) and low trait anxiety (LTA) were selected from a total of 803 college students. These participants then completed a two-digit multiplication estimation task after using cognitive reappraisal to regulate negative emotions. Results: The results showed that for individuals with low trait anxiety, both standard cognitive reappraisal and creative cognitive re
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28

OLLIVIER, L., L. A. MESSER, M. F. ROTHSCHILD, and C. LEGAULT. "The use of selection experiments for detecting quantitative trait loci." Genetical Research 69, no. 3 (1997): 227–32. http://dx.doi.org/10.1017/s0016672397002802.

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Gene frequency changes following selection may reveal the existence of gene effects on the trait selected. Loci for the selected quantitative trait (SQTL) may thus be detected. Additionally, one can estimate the average effect (α) of a marker allele associated with an SQTL from the allele frequency change (Δq) due to selection of given intensity (i). In a sample of unrelated individuals, it is optimal to select the upper and lower 27% for generating Δq in order to estimate α. For a given number of individuals genotyped, this estimator is 0·25i2 times more efficient than the classical estimator
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Hou, Lixin, Yuxia Zhu, Mengke Wang, et al. "Multimodal Data Fusion for Precise Lettuce Phenotype Estimation Using Deep Learning Algorithms." Plants 13, no. 22 (2024): 3217. http://dx.doi.org/10.3390/plants13223217.

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Effective lettuce cultivation requires precise monitoring of growth characteristics, quality assessment, and optimal harvest timing. In a recent study, a deep learning model based on multimodal data fusion was developed to estimate lettuce phenotypic traits accurately. A dual-modal network combining RGB and depth images was designed using an open lettuce dataset. The network incorporated both a feature correction module and a feature fusion module, significantly enhancing the performance in object detection, segmentation, and trait estimation. The model demonstrated high accuracy in estimating
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Greveniotis, Vasileios, Evangelia Sioki, and Constantinos G. Ipsilandis. "Estimations of fibre trait stability and type of inheritance in cotton." Czech Journal of Genetics and Plant Breeding 54, No. 4 (2018): 190–92. http://dx.doi.org/10.17221/12/2017-cjgpb.

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Traits affecting fibre quality were evaluated in a multi-location environmental experiment. Four main cotton regions in Greece were selected as different environments. Five commercial cotton cultivars were used for evaluation of 10 fibre quality traits. Each cultivar was sown in 10 different fields in each region. Environmental fluctuations within regions affected each quality trait differently showing a different degree of inheritance. Four traits showed the lowest stability index values indicating quantitative inheritance, further four traits with intermediate values indicated determination
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Sisson, S. A., and M. A. Hurn. "Bayesian Point Estimation of Quantitative Trait Loci." Biometrics 60, no. 1 (2004): 60–68. http://dx.doi.org/10.1111/j.0006-341x.2004.00167.x.

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Meijer, Rob R., and Michael L. Nering. "Trait Level Estimation for Nonfitting Response Vectors." Applied Psychological Measurement 21, no. 4 (1997): 321–36. http://dx.doi.org/10.1177/01466216970214003.

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Di Croce, F. A., A. M. Saxton, N. R. Rohrbach, and F. N. Schrick. "138 GENETIC PARAMETER ESTIMATION FOR EMBRYO TRANSFER TRAITS." Reproduction, Fertility and Development 21, no. 1 (2009): 169. http://dx.doi.org/10.1071/rdv21n1ab138.

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Genetic selection has made tremendous progress on economically important traits in the beef industry. Most of the progress has been from quantitative genetics through use of expected progeny differences (EPD). These values allow prediction of differences in progeny of a sire compared to progeny of other sires. Development of EPD for male and female reproductive traits has largely been ignored because of low heritability of reproductive traits, even though reproduction plays a vital role in the economics of beef operations. Therefore, continued research in the area of genetic selection for fert
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Ohlert, Timothy, Kaitlin Kimmel, Meghan Avolio, et al. "The impact of trait number and correlation on functional diversity metrics in real-world ecosystems." PLOS ONE 19, no. 9 (2024): e0306342. http://dx.doi.org/10.1371/journal.pone.0306342.

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The use of trait-based approaches to understand ecological communities has increased in the past two decades because of their promise to preserve more information about community structure than taxonomic methods and their potential to connect community responses to subsequent effects of ecosystem functioning. Though trait-based approaches are a powerful tool for describing ecological communities, many important properties of commonly-used trait metrics remain unexamined. Previous work with simulated communities and trait distributions shows sensitivity of functional diversity measures to the n
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Moawed, Sherif. "A Comparison Between Single-Trait Statistical Model and Multi-Traits Model for The Genetic Evaluation of Dairy Cattle Populations Raised in Egypt." Alexandria Journal of Veterinary Sciences 83 (2024): 65. http://dx.doi.org/10.5455/ajvs.198801.

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The incorporation of modern animal models become imperative for planning breeding strategies of dairy populations. The present study was designed to compare between single-trait and multi-traits animal models in estimating genetic parameters and breeding values for some milk yield and reproductive traits of Holstein-Friesian dairy cattle. A total of 9450 records of dairy cows calved in the period between 2007 and 2018 were included in the analyses by using the datasets of the first four lactations. Mixed model methodologies have been applied through applications of restricted maximum likelihoo
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Wael Mahmood, Hussein, and Zakariya Bader Al Hamdani. "Estimation of genetic parameters for new entries of bread wheat (Triticum aestivum L.)." Sumer 4 8, CSS 4 (2023): 1–8. http://dx.doi.org/10.21931/rb/css/2023.08.04.65.

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The study was conducted in one of the fields of the Al-Yamja area, south of Mosul, which is (5) km from the city Centre for the season (2020-2021). Five genotypes of soft wheat were used, which were obtained from the Organization (C.I.M.M.Y.T.), adding an approved local cultivar (Abu Ghraib). The cultivation was carried out on lines with a length of (2) m and the distance between one line and another (30) cm using a randomized complete block design (R.C.B.D.) with three replications and in the manner explained by 1 .The study included the following traits: number of days to flowering at (50%),
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Jiang, C., and Z. B. Zeng. "Multiple trait analysis of genetic mapping for quantitative trait loci." Genetics 140, no. 3 (1995): 1111–27. http://dx.doi.org/10.1093/genetics/140.3.1111.

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Abstract We present in this paper models and statistical methods for performing multiple trait analysis on mapping quantitative trait loci (QTL) based on the composite interval mapping method. By taking into account the correlated structure of multiple traits, this joint analysis has several advantages, compared with separate analyses, for mapping QTL, including the expected improvement on the statistical power of the test for QTL and on the precision of parameter estimation. Also this joint analysis provides formal procedures to test a number of biologically interesting hypotheses concerning
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Sosa-Madrid, Bolívar Samuel, Gerasimos Maniatis, Noelia Ibáñez-Escriche, Santiago Avendaño, and Andreas Kranis. "Genetic Variance Estimation over Time in Broiler Breeding Programmes for Growth and Reproductive Traits." Animals 13, no. 21 (2023): 3306. http://dx.doi.org/10.3390/ani13213306.

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Monitoring the genetic variance of traits is a key priority to ensure the sustainability of breeding programmes in populations under directional selection, since directional selection can decrease genetic variation over time. Studies monitoring changes in genetic variation have typically used long-term data from small experimental populations selected for a handful of traits. Here, we used a large dataset from a commercial breeding line spread over a period of twenty-three years. A total of 2,059,869 records and 2,062,112 animals in the pedigree were used for the estimations of variance compon
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Ohlert, Timothy, Kaitlin Kimmel, Meghan Avolio, et al. "Exploring the impact of trait number and type on functional diversity metrics in real-world ecosystems." PLOS ONE 17, no. 8 (2022): e0272791. http://dx.doi.org/10.1371/journal.pone.0272791.

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The use of trait-based approaches to understand ecological communities has increased in the past two decades because of their promise to preserve more information about community structure than taxonomic methods and their potential to connect community responses to subsequent effects of ecosystem functioning. Though trait-based approaches are a powerful tool for describing ecological communities, many important properties of commonly-used trait metrics remain unexamined. Previous work in studies that simulate communities and trait distributions show consistent sensitivity of functional richnes
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Steinfeld, Jan, and Alexander Robitzsch. "Item Parameter Estimation in Multistage Designs: A Comparison of Different Estimation Approaches for the Rasch Model." Psych 3, no. 3 (2021): 279–307. http://dx.doi.org/10.3390/psych3030022.

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There is some debate in the psychometric literature about item parameter estimation in multistage designs. It is occasionally argued that the conditional maximum likelihood (CML) method is superior to the marginal maximum likelihood method (MML) because no assumptions have to be made about the trait distribution. However, CML estimation in its original formulation leads to biased item parameter estimates. Zwitser and Maris (2015, Psychometrika) proposed a modified conditional maximum likelihood estimation method for multistage designs that provides practically unbiased item parameter estimates
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Lamour, Julien, Kenneth J. Davidson, Kim S. Ely, et al. "Rapid estimation of photosynthetic leaf traits of tropical plants in diverse environmental conditions using reflectance spectroscopy." PLOS ONE 16, no. 10 (2021): e0258791. http://dx.doi.org/10.1371/journal.pone.0258791.

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Tropical forests are one of the main carbon sinks on Earth, but the magnitude of CO2 absorbed by tropical vegetation remains uncertain. Terrestrial biosphere models (TBMs) are commonly used to estimate the CO2 absorbed by forests, but their performance is highly sensitive to the parameterization of processes that control leaf-level CO2 exchange. Direct measurements of leaf respiratory and photosynthetic traits that determine vegetation CO2 fluxes are critical, but traditional approaches are time-consuming. Reflectance spectroscopy can be a viable alternative for the estimation of these traits
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42

Misztal, Ignacy. "295 Parameter estimation under genomic selection." Journal of Animal Science 98, Supplement_4 (2020): 31–32. http://dx.doi.org/10.1093/jas/skaa278.056.

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Abstract Genetic parameters are important in animal breeding for many tasks, including as input to a model for genetic evaluation, to estimate genetic gain due to selection, and to estimate correlated response due to selection on major traits. Before the genomic era, parameter estimation was facilitated by sparse structure of mixed model equations. Methods such as AI REML with sparse matrix inversion or MCMC via Gibbs sampling could estimate parameters for populations exceeding 1 million animals. With genomic selection (GS) and single-step GBLUP, the genomic matrices are mostly dense, and cost
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Azevedo Junior, Jairo, Juliana Petrini, Gerson Barreto Mourão, and José Bento Sterman Ferraz. "Categorical Visual Score Traits of a Nellore Beef Cattle Population." Journal of Agricultural Science 9, no. 8 (2017): 63. http://dx.doi.org/10.5539/jas.v9n8p63.

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Variance components and genetic parameters of economically relevant traits in livestock, whether continuous or categorical, can be estimated by methods computationally available providing support for the selection and mating of animals in breeding programs. The objectives of this paper were to obtain and compare the variance components estimates for visual traits under continuous or categorical distribution in single-trait analysis and their correlations with continuous productive traits in two-trait analysis. Data of conformation (CONF), precocity of fat deposition (PREC) and muscling (MUSC)
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Krapinec, Krešimir, Vlado Jumić, Matija Balekić, et al. "The Reliability of Fluctuating Asymmetry in Population Estimation: The Case of Feedlot Red Deer." Symmetry 14, no. 10 (2022): 2092. http://dx.doi.org/10.3390/sym14102092.

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Three FA indices showed correlations with age and magnitude of traits, but not in general. Significant correlations between magnitude of traits and their FA were more pronounced in AFA (12 traits) than in RFA (10 traits) in all age classes except yearlings. For the tray tine form (curvature), FA significantly correlated with its magnitude in young, middle-aged and ripe stags, which indicates that the trait is a reliable indicator of asymmetry. Significant differences in AFA among age classes were found in four traits (weight of dry antlers, volume of antlers, distal circumference of beams and
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Roka, Punam, Suraj Shrestha, Shiva Prasad Adhikari, Ayushma Neupane, Briksha Shreepaili, and Mohan Kumar Bista. "A review on genetic parameters estimation, trait association, and multivariate analysis for crop improvement." Archives of Agriculture and Environmental Science 9, no. 3 (2024): 618–25. http://dx.doi.org/10.26832/24566632.2024.0903029.

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This review paper aims to elucidate the critical genetic parameters essential for practical crop breeding, focusing on the nature and extent of variability, its inheritance, and the complexity of traits. By evaluating genetic parameters such as Genetic Coefficient of Variation (G.C.V.), Heritability, Genetic Advance as a percentage of the Mean (G.A.M.), correlation coefficients, path coefficient analysis, cluster analysis, and principal component analysis, the review provides a comprehensive framework for optimizing breeding strategies. Emphasizing higher G.C.V. values minimizes environmental
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Robitzsch, Alexander. "About the Equivalence of the Latent D-Scoring Model and the Two-Parameter Logistic Item Response Model." Mathematics 9, no. 13 (2021): 1465. http://dx.doi.org/10.3390/math9131465.

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This article shows that the recently proposed latent D-scoring model of Dimitrov is statistically equivalent to the two-parameter logistic item response model. An analytical derivation and a numerical illustration are employed for demonstrating this finding. Hence, estimation techniques for the two-parameter logistic model can be used for estimating the latent D-scoring model. In an empirical example using PISA data, differences of country ranks are investigated when using different metrics for the latent trait. In the example, the choice of the latent trait metric matters for the ranking of c
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Garriga, M., C. Ovalle, S. Espinoza, G. A. Lobos, and A. del Pozo. "Use of Vis–NIR reflectance data and regression models to estimate physiological and productivity traits in lucerne (Medicago sativa)." Crop and Pasture Science 71, no. 1 (2020): 90. http://dx.doi.org/10.1071/cp19182.

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Lucerne (alfalfa, Medicago sativa L.) is grown extensively worldwide owing to its high forage biomass production and nutritional value. Although this crop is characterised as being tolerant to drought, its production and persistence are affected by water stress. Selection of genotypes of high yield potential and persistence after a long period of drought is a major objective for lucerne-breeding programmes in Mediterranean environments. This selection could be enhanced and accelerated by the use of physiological and productivity traits and their estimation through remote-sensing methods. A set
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Southwood, O. I. "Estimation of genetic and phenotypic trends for litter size in canadian yorkshire and landrace swine." Proceedings of the British Society of Animal Production (1972) 1990 (March 1990): 12. http://dx.doi.org/10.1017/s0308229600017967.

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Litter size in swine, although lowly heritable, has been receiving increasing interest especially with the availability of computer programs to allow estimation of genetic merit for this trait using family information. Genetic changes in a trait over time can be monitored by estimating best linear unbiased prediction (BLUP) of breeding value for individuals exhibiting the trait. Data from a recording programme within a Canadian province allowed estimation of genetic and phenotypic trends for three measures of litter size.Data from purebred Yorkshire and Landrace litters were obtained from the
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TAN, QIHUA, LENE CHRISTIANSEN, KAARE CHRISTENSEN, et al. "Haplotype association analysis of human disease traits using genotype data of unrelated individuals." Genetical Research 86, no. 3 (2005): 223–31. http://dx.doi.org/10.1017/s0016672305007792.

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Haplotype inference has become an important part of human genetic data analysis due to its functional and statistical advantages over the single-locus approach in linkage disequilibrium mapping. Different statistical methods have been proposed for detecting haplotype – disease associations using unphased multi-locus genotype data, ranging from the early approach by the simple gene-counting method to the recent work using the generalized linear model. However, these methods are either confined to case – control design or unable to yield unbiased point and interval estimates of haplotype effects
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Bi, Kaiyi, Zheng Niu, Shunfu Xiao, et al. "Estimation of Maize Photosynthesis Traits Using Hyperspectral Lidar Backscattered Intensity." Remote Sensing 13, no. 21 (2021): 4203. http://dx.doi.org/10.3390/rs13214203.

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High-throughput measurement of plant photosynthesis ability presents a challenge for the breeding process aimed to improve crop yield. As a novel technique, hyperspectral lidar (HSL) has the potential to characterize the spatial distribution of plant photosynthesis traits under less confounding factors. In this paper, HSL reflectance spectra of maize leaves were utilized for estimating the maximal velocity of Rubisco carboxylation (Vcmax) and maximum rate of electron transport at a specific light intensity (J) based on both reflectance-based and trait-based methods, and the results were compar
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