Log in

Relevant bibliographies by topics / Analysis of variance (ANOVA) eng / Dissertations / Theses

To see the other types of publications on this topic, follow the link: Analysis of variance (ANOVA) eng.

Dissertations / Theses on the topic 'Analysis of variance (ANOVA) eng'

Author: Grafiati

Published: 4 June 2021

Last updated: 1 February 2022

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 31 dissertations / theses for your research on the topic 'Analysis of variance (ANOVA) eng.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.

1

Gonsalez, Camila Gianini. "Metodologias para reconhecimento de padrões em sistemas SHM utilizando a técnica da Impedância Eletromecânica (E/M) /." Ilha Solteira : [s.n.], 2012. http://hdl.handle.net/11449/94506.

Full text

Abstract:

Orientador: Vicente Lopes Junior<br>Banca: Samuel Silva<br>Banca: Michael John Brennan<br>Banca: Carlos Alberto Cimini Junior<br>Resumo: Pesquisadores de diversas partes do mundo se empenham em desenvolver técnicas capazes de monitorar a integridade de máquinas, veículos e estruturas, principalmente as que a ruptura ou destruição possa provocar acidentes e catástrofes. Neste contexto, várias técnicas não destrutivas podem ser utilizadas para monitorar estes sistemas permitindo a realização de reparos e, evitando maiores prejuízos econômicos e danos sociais. A técnica da Impedância Eletromecâni

APA, Harvard, Vancouver, ISO, and other styles

2

Prosser, Robert James. "Robustness of multivariate mixed model ANOVA." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25511.

Full text

Abstract:

In experimental or quasi-experimental studies in which a repeated measures design is used, it is common to obtain scores on several dependent variables on each measurement occasion. Multivariate mixed model (MMM) analysis of variance (Thomas, 1983) is a recently developed alternative to the MANOVA procedure (Bock, 1975; Timm, 1980) for testing multivariate hypotheses concerning effects of a repeated factor (called occasions in this study) and interaction between repeated and non-repeated factors (termed group-by-occasion interaction here). If a condition derived by Thomas (1983), multivariate

APA, Harvard, Vancouver, ISO, and other styles

3

Halldestam, Markus. "ANOVA - The Effect of Outliers." Thesis, Uppsala universitet, Statistiska institutionen, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-295864.

Full text

Abstract:

This bachelor’s thesis focuses on the effect of outliers on the one-way analysis of variance and examines whether the estimate in ANOVA is robust and whether the actual test itself is robust from influence of extreme outliers. The robustness of the estimates is examined using the breakdown point while the robustness of the test is examined by simulating the hypothesis test under some extreme situations. This study finds evidence that the estimates in ANOVA are sensitive to outliers, i.e. that the procedure is not robust. Samples with a larger portion of extreme outliers have a higher type-I er

APA, Harvard, Vancouver, ISO, and other styles

4

Patrick, Joshua Daniel. "Simulations to analyze Type I error and power in the ANOVA F test and nonparametric alternatives." [Pensacola, Fla.] : University of West Florida, 2009. http://purl.fcla.edu/fcla/etd/WFE0000158.

Full text

APA, Harvard, Vancouver, ISO, and other styles

5

Lind, Ingela. "Regressor and Structure Selection : Uses of ANOVA in System Identification." Doctoral thesis, Linköping : Linköpings universitet, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-7000.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

An, Qian. "A Monte Carlo study of several alpha-adjustment procedures using a testing multiple hypotheses in factorial anova." Ohio : Ohio University, 2010. http://www.ohiolink.edu/etd/view.cgi?ohiou1269439475.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

Jordaan, Aletta Gertruida. "Empirical Bayes estimation of the extreme value index in an ANOVA setting." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86216.

Full text

Abstract:

Thesis (MComm)-- Stellenbosch University, 2014.<br>ENGLISH ABSTRACT: Extreme value theory (EVT) involves the development of statistical models and techniques in order to describe and model extreme events. In order to make inferences about extreme quantiles, it is necessary to estimate the extreme value index (EVI). Numerous estimators of the EVI exist in the literature. However, these estimators are only applicable in the single sample setting. The aim of this study is to obtain an improved estimator of the EVI that is applicable to an ANOVA setting. An ANOVA setting lends itself naturally to

APA, Harvard, Vancouver, ISO, and other styles

8

Zhang, Bairu. "Functional data analysis in orthogonal designs with applications to gait patterns." Thesis, Queen Mary, University of London, 2018. http://qmro.qmul.ac.uk/xmlui/handle/123456789/44698.

Full text

Abstract:

This thesis presents a contribution to the active research area of functional data analysis (FDA) and is concerned with the analysis of data from complex experimental designs in which the responses are curves. High resolution, closely correlated data sets are encountered in many research fields, but current statistical methodologies often analyse simplistic summary measures and therefore limit the completeness and accuracy of conclusions drawn. Specifically the nature of the curves and experimental design are not taken into account. Mathematically, such curves can be modelled either as sample

APA, Harvard, Vancouver, ISO, and other styles

9

Messetti, Ana Vergínia Libos 1964. "Utilização de técnicas multivariadas na avaliação da divergência genética de populações de girassol (Helianthus annuus L.) /." Botucatu : [s.n.], 2007. http://hdl.handle.net/11449/101858.

Full text

Abstract:

Orientador: Carlos Roberto Padovani<br>Banca: Adriano Wagner Ballarin<br>Banca: José Carlos Martinez<br>Banca: Jacinta Ludovico Zamboti<br>Banca: Marie Oshiiwa<br>Resumo: Este trabalho foi desenvolvido com os objetivos de avaliar a divergência genética de 12 populações de girassol do Banco de Germoplasma da EMBRAPA /Soja de Londrina por meio de técnicas multivariadas; divulgar tópicos recentes e interessantes das técnicas multivariadas que não são explorados nos trabalhos científicos de melhoramento de plantas e orientar a escolha de populações para cruzamentos nos programas de melhoramento ge

APA, Harvard, Vancouver, ISO, and other styles

10

Gonsalez, Camila Gianini [UNESP]. "Metodologias para reconhecimento de padrões em sistemas SHM utilizando a técnica da Impedância Eletromecânica (E/M)." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/94506.

Full text

Abstract:

Made available in DSpace on 2014-06-11T19:27:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-02-24Bitstream added on 2014-06-13T19:14:27Z : No. of bitstreams: 1 gonsalez_cg_me_ilha.pdf: 4679748 bytes, checksum: 5f6a627734b2110f92059053c2470814 (MD5)<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>Pesquisadores de diversas partes do mundo se empenham em desenvolver técnicas capazes de monitorar a integridade de máquinas, veículos e estruturas, principalmente as que a ruptura ou destruiç

APA, Harvard, Vancouver, ISO, and other styles

11

Joubert, Ronel. "Factors influencing the degree of burnout experienced by nurses working in neonatal intensive care units." Thesis, Stellenbosch : Stellenbosch University, 2012. http://hdl.handle.net/10019.1/20217.

Full text

Abstract:

Thesis (MCur)--Stellenbosch University, 2012.<br>ENGLISH ABSTRACT: Burnout is one of the challenges that nurses are faced with in their stressful and rapidly changing work environment. The vulnerability of nurses to burnout remains a major concern which affects both the individual and institution. Knowledge about burnout and associated risk factors which influence the development of burnout is vital for early recognition and intervention. The research question which guided this study was: “What are the factors influencing the degree of burnout experienced by nurses working in neonatal in

APA, Harvard, Vancouver, ISO, and other styles

12

Höög, Andrée, and Christoffer Wrangenby. "Studenters förhållning till Javas kodkonventioner inom högskoleingenjörsutbildningar i Sverige - En komparativ studie." Thesis, Malmö högskola, Fakulteten för teknik och samhälle (TS), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:mau:diva-20454.

Full text

Abstract:

Att sätta sig in i andra utvecklares kod kan vara svårt och tidskrävande. Kodkonventionerär framtagna i syfte att underlätta underhållsarbetet för andra utvecklare som arbetar medsamma projekt, då det sällan är personen som skrev programmet som sedan underhållersamma program. För lite fokus läggs på kvalitétsaspekten i utvecklingsfasen av projektvilket kostar företag pengar och resurser. Denna studie har för avsikt att undersöka hurhögskoleingenjörsstudenter inom datateknik vid olika lärosäten i Sverige förhåller sig tillJavas kodkonventioner, och om det går att urskilja en signifikant skillna

APA, Harvard, Vancouver, ISO, and other styles

13

Varanda, Luciano Donizeti. "Produção e avaliação do desempenho de painéis de partículas de Eucalyptus grandis confeccionados com adição de casca de aveia." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-09082012-165028/.

Full text

Abstract:

Os painéis à base de madeira vêm sendo amplamente utilizados em todo o mundo, em resposta à redução de oferta de madeira maciça em diversos segmentos da indústria madeireira, como em móveis, painéis, estruturas e outros componentes na construção civil. O grande volume de resíduos gerados pela agroindústria viabiliza o desenvolvimento de materiais alternativos e sustentáveis, destacando-se os painéis de partículas. Este trabalho apresenta um estudo da produção e avaliação de painéis de partículas de Eucalyptus grandis e casca de aveia, aderidas sob pressão com dois tipos de resinas (poliuretana

APA, Harvard, Vancouver, ISO, and other styles

14

Landim, Karine Tenório. "Estudo da influência da ciclagem mecânica sobre a resistência de união ao cisalhamento entre uma cerâmica de recobrimento estético e duas cerâmicas infiltradas por vidro /." São José dos Campos : [s.n.], 2006. http://hdl.handle.net/11449/97410.

Full text

Abstract:

Orientador: Renato Sussumu Nishioka<br>Banca: Osvaldo Daniel Andreatta Filho<br>Banca: Lafayette Nogueira Junior<br>Resumo: Este estudo avaliou a influência da ciclagem mecânica na resistência de união ao cisalhamento entre cerâmicas infiltradas por vidro para infra-estrutura (In-Ceram Alumina - Vita Zahnfabrik e In-Ceram Zircônia - Vita Zahnfabrik) e uma cerâmica vítrea de recobrimento (VITA VM7 - Vita Zahnfabrik). Foram preparadas vinte e quatro amostras cilíndricas nas dimensões de 4mm de diâmetro por 5mm de altura para cada cerâmica de infra-estrutura. Posteriormente, a cerâmica de recobri

APA, Harvard, Vancouver, ISO, and other styles

15

Copeland, Matthew Blair. "Learner Modal Preference and Content Delivery Method Predicting Learner Performance and Satisfaction." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc862858/.

Full text

Abstract:

The purpose of the study was to investigate how the online, computer-based learner's personal learning profile (Preference), the content delivery method supplemented with visual content based on Neil Fleming's VARK (visual, aural, read/write, kinesthetic) model (Content), and the interaction of Preference and Content, influenced learner performance (Performance) and/or learner self-reported satisfaction (Satisfaction). Participants were drawn from a population of undergraduates enrolled in a large public southwestern research university during the fall 2015 semester. The 165 student participa

APA, Harvard, Vancouver, ISO, and other styles

16

Haddad, Samia Ramos 1978. "Aplicação de modelos lineares para análise de expressão gênica em experimentos de microarrays /." Botucatu : [s.n.], 2007. http://hdl.handle.net/11449/95296.

Full text

Abstract:

Orientador: Henrique Nunes de Oliveira<br>Banca: Raysildo Barbosa Lobo<br>Banca: Danísio Prado Munari<br>Resumo: O presente trabalho objetivou comparar, utilizando dados de um experimento de Microarray com um delineamento simples, os resultados de diferentes testes estatísticos a fim de verificar suas características na detecção de diferenças no nível de expressão dos genes. Os dados foram provenientes da South Dakota State University-EUA, do Department of Biology and Microbiology, Department of Animal Science, onde toda a parte experimental foi realizada. O material biológico envolveu quatro

APA, Harvard, Vancouver, ISO, and other styles

17

Firoozmand, Leily Macedo. "Avaliação da microdureza superficial da resina composta fotopolimerizada por aparelho de luz halógena e de diodo(LED) em função de opacidade e ação do flúor fosfato acidulado /." São José dos Campos : [s.n.], 2005. http://hdl.handle.net/11449/89622.

Full text

Abstract:

Orientador: Maria Amélia Máximo de Araújo<br>Banca: Maria Amélia Máximo de Araújo<br>Banca: Maria Antonia Pereira<br>Banca: João Carlos da Rocha<br>Resumo: O objetivo deste trabalho foi verificar a influência da opacidade de cor, tipos de aparelhos fotopolimerizadores (luz halogena X led azul) e aplicação tópica do FFA 1,23% na microdureza da resina composta. A resina composta Esthet-X (Dentisply), nas cores A2 e A2-O foram inseridas em uma matriz de aço-inoxidável em cavidades de 5mm de diâmetro e 2mm de profundidade e fotopolimerizadas por aparelhos; de luz halogena, XL 3000 (3M) ou de LED a

APA, Harvard, Vancouver, ISO, and other styles

18

Varanda, Luciano Donizeti. "Painéis de alta densidade para aplicação em pisos: produção e avaliação de desempenho." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-16112016-174123/.

Full text

Abstract:

Temas relacionados ao desenvolvimento de novos materiais têm sido cada vez mais abordados e discutidos, num contexto em que questões como meio ambiente, sociedade, economia de energia e aproveitamento de resíduos, vêm se tornando relevantes. Neste cenário, faz-se necessário estudar aplicações de insumos alternativos na produção de pisos de madeira, tanto para reduzir o consumo de essências tropicais quanto para suprir o aumento da demanda de madeira nas indústrias deste segmento. O objetivo deste estudo foi produzir painéis de partículas homogêneos de alta densidade, com resíduos de madeira de

APA, Harvard, Vancouver, ISO, and other styles

19

Mankayi, Dolphia Thozama. "An investigation into the relationship between satisfaction with life and sense of coherence amongst the unemployed." University of the Western Cape, 1996. http://hdl.handle.net/11394/7861.

Full text

Abstract:

Magister Commercii (Industrial Psychology) - MCom(IPS)<br>The present study investigated the relationship between the Sense Of Coherence and Satisfaction With Life amongst the unemployed. The study attempted to test the following hypotheses. 1. People with a high Sense Of Coherence tend to be satisfied with their lives in general. 2. Demographic variables such as age, gender, race and level of education have an influence on the subjects' scores on the Sense Of Coherence and Satisfaction With Life scales. 3. Length of unemployment has an impact on the subjects' Sense Of Coherence and Satisfact

APA, Harvard, Vancouver, ISO, and other styles

20

Souza, Amós Magalhães de. "Produção e avaliação do desempenho de compósitos à base de madeira a partir de insumos alternativos." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-27112017-102235/.

Full text

Abstract:

A utilização de produtos provenientes de fontes renováveis e livres de substâncias tóxicas é tendência global, prova disso é o constante aumento da demanda por produtos à base de madeira. Segundo o Forest Products Statistics (2015), a produção mundial de painéis de madeira reconstituída, em 2014, foi de 388 milhões de m³, um aumento de 5,5% em comparação com o ano anterior e um aumento de 34% quando comparado com 2010. No entanto, o setor industrial de painéis de madeira há décadas enfrenta um grande desafio com relação às emissões tóxicas vindas dos adesivos convencionais. Diante destes probl

APA, Harvard, Vancouver, ISO, and other styles

21

Aroge, Olatunde O. "Assessment Of Disruption Risk In Supply Chain The Case Of Nigeria’s Oil Industry." Thesis, University of Bradford, 2018. http://hdl.handle.net/10454/17396.

Full text

Abstract:

evaluate disruption risks in the supply chain of petroleum production. This methodology is developed to formalise and facilitate the systematic integration and implementation of various models; such as analytical hierarchy process (AHP) and partial least squares structural equation model (PLS-SEM) and various statistical tests. The methodology is validated with the case of Nigeria’s oil industry. The study revealed the need to provide a responsive approach to managing the influence of geopolitical risk factors affecting supply chain in the petroleum production industry. However, the explorati

APA, Harvard, Vancouver, ISO, and other styles

22

Veleba, Ondřej. "Studium vlivu složení na mechanické vlastnosti vysokohodnotného betonu." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2008. http://www.nusl.cz/ntk/nusl-216217.

Full text

Abstract:

This work is devoted to study the influence of the composition on mechanical properties of high performance concret based on portland cement. 29 samples of high performance concrete (HPC) warying in composition were prepared. The constituents used for HPC preparation were: cement Aalborg White, silica fume, finelly ground blast furnace slag, finelly ground silica, calcinated bauxite and polycarboxylate based superplasticizer. The mechanical parameters (flexural and compressive strength) of the samples were observed after 7 and 28 days of moist curing. Compressive strength values after 28 days

APA, Harvard, Vancouver, ISO, and other styles

23

Léal, Françoise. "Etude de la production et de l'émanation de composés volatils malodorants sur textile à usage sportif." Thesis, Vandoeuvre-les-Nancy, INPL, 2011. http://www.theses.fr/2011INPL070N/document.

Full text

Abstract:

Si la sueur fraîchement émise par le corps humain est inodore, la dégradation de celle-ci par la flore bactérienne cutanée produit des composés volatils malodorants, responsables des odeurs de transpiration. Les odeurs de transpiration apparaissent également sur les vêtements au cours de leur utilisation, particulièrement sur les textiles réalisés en fibres synthétiques. Ce travail a pour but d’améliorer la compréhension du phénomène d’émanation d’odeurs en étudiant l’effet du sujet testé, l’effet de la flore bactérienne et l’effet du textile sur les émissions de composés volatils malodorants.

APA, Harvard, Vancouver, ISO, and other styles

24

Krummenauer, Alex. "Desenvolvimento e validação de metodologia analítica para análise de aços por espectrometria de fluorescência de raios X por dispersão de energia (EDXRF)." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2017. http://hdl.handle.net/10183/178232.

Full text

Abstract:

O desenvolvimento e validação de métodos analíticos é um procedimento necessário quando um método não normalizado é utilizado por um laboratório de ensaios. A validação de métodos também é um requisito específico da norma ABNT NBR ISO/IEC 17025, que determina os requisitos gerais para a competência dos laboratórios de ensaio e calibração. O objetivo da validação é demonstrar que o método analítico, nas condições em que é executado, produz resultados com a exatidão requerida. O Laboratório de Corrosão, Proteção e Reciclagem de Materiais (LACOR), da UFRGS, tem o ensaio de determinação de metais

APA, Harvard, Vancouver, ISO, and other styles

25

Oakley, Florence. "Generational differences in the frequency and importance of meaningful work." Thesis, University of Canterbury. Department of Management, 2015. http://hdl.handle.net/10092/10931.

Full text

Abstract:

This thesis aimed to investigate generational differences in the frequency and importance of meaningful work in employees based on the 7 facets of the Map of Meaning. Hypotheses were tested through Analysis of Variance of secondary data. 395 participants self-reported levels of meaningful work on the Comprehensive Meaningful Work Scale. Results indicated that Generation Y had significantly lower levels of meaningful work. Generation Y had significantly lower levels of Unity (importance), Serving (frequency and importance), Expressing full potential (frequency), Reality (frequency and importanc

APA, Harvard, Vancouver, ISO, and other styles

26

Belmar, Gil Mario. "Computational study on the non-reacting flow in Lean Direct Injection gas turbine combustors through Eulerian-Lagrangian Large-Eddy Simulations." Doctoral thesis, Universitat Politècnica de València, 2021. http://hdl.handle.net/10251/159882.

Full text

Abstract:

[ES] El principal desafío en los motores turbina de gas empleados en aviación reside en aumentar la eficiencia del ciclo termodinámico manteniendo las emisiones contaminantes por debajo de las rigurosas restricciones. Ésto ha conllevado la necesidad de diseñar nuevas estrategias de inyección/combustión que operan en puntos de operación peligrosos por su cercanía al límite inferior de apagado de llama. En este contexto, el concepto Lean Direct Injection (LDI) ha emergido como una tecnología prometedora a la hora de reducir los óxidos de nitrógeno (NOx) emitidos por las plantas propulsoras de lo

APA, Harvard, Vancouver, ISO, and other styles

27

Zhang, Lan. "From Martingales to ANOVA : implied and realized volatility /." 2001. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:3006569.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Chaka, Lyson. "Impact of unbalancedness and heteroscedasticity on classic parametric significance tests of two-way fixed-effects ANOVA tests." Diss., 2016. http://hdl.handle.net/10500/23287.

Full text

Abstract:

Classic parametric statistical tests, like the analysis of variance (ANOVA), are powerful tools used for comparing population means. These tests produce accurate results provided the data satisfies underlying assumptions such as homoscedasticity and balancedness, otherwise biased results are obtained. However, these assumptions are rarely satisfied in real-life. Alternative procedures must be explored. This thesis aims at investigating the impact of heteroscedasticity and unbalancedness on effect sizes in two-way fixed-effects ANOVA models. A real-life dataset, from which three different

APA, Harvard, Vancouver, ISO, and other styles

29

Patel, Mitra Kumar. "The Effects of Social Capital and Open Innovation on R&D Outcomes and Job Satisfaction : A Study of The Indian Deference Sector." Thesis, 2017. http://etd.iisc.ernet.in/2005/3781.

Full text

Abstract:

Social Capital and Open Innovation are important for organisational growth, as both of them influence Innovation, Learning and Job Satisfaction. The literature indicates that informal network measured as social capital and formal network measured as open innovation influences positively to organizational innovation performance, learning and job satisfaction. Most of the studies in this area have been carried out using univariate approaches, and only few dimensions of both Social Capital and Open Innovation have been considered. Current literature outlines the positive influence of Social Capit

APA, Harvard, Vancouver, ISO, and other styles

30

Nyembe, Bangisisi Zamuxolo Mathews. "Measuring Mobile Collaborative Learning and academic achievement : whatsapp and students in South Africa." Diss., 2021. http://hdl.handle.net/10500/27566.

Full text

Abstract:

Mobile learning has developed into an essential component within the education landscape and, with two billion users worldwide, the social media platform WhatsApp has become a prominent feature in this domain. Nevertheless, with ambiguity in the literature about the effects of WhatsApp on teaching and learning and especially a paucity of research measuring collaboration on WhatsApp in relation to students’ academic achievement. The purpose of the study was to explain and predict WhatsApp’s effect on academic achievement using a quantitative questionnaire. The results suggest that increased col

APA, Harvard, Vancouver, ISO, and other styles

31

David, Joanne Munro. "An evaluation of the effectiveness of a cognitive load based teaching method in a mixed ability grade 9 class, with special attention to learners' attitudes and engagement." Diss., 2015. http://hdl.handle.net/10500/21803.

Full text

APA, Harvard, Vancouver, ISO, and other styles

We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!