Dulce Gamito Pereira

A comparison between Joint Regression Analysis and the Additive Main and Multiplicative Interaction model: the robustness with increasing amounts of missing data

This paper joins the main properties of joint regression analysis (JRA), a model based on the Finlay-Wilkinson regression to analyse multi-environment trials, and of the additive main effects and multiplicative interaction (AMMI) model. The study compares JRA and AMMI with particular focus on robustness with increasing amounts of randomly selected missing data. The application is made using a data set from a breeding program of durum wheat (Triticum turgidum L., Durum Group) conducted in Portugal. The results of the two models result in similar dominant cultivars (JRA) and winner of mega-environments (AMMI) for the same environments. However, JRA had more stable results with the increase in the incidence rates of missing values.

Evaluation of elderly persons' functionality and care needs

OBJETIVO: avaliar a funcionalidade dos idosos com base na Classificacao Internacional da Funcionalidade. METODOS: estudo transversal, descritivo; amostra aleatoria, estratificada, com 903 idosos; nivel de confianca 95%; margem de erro 2,5%. Questionario desenvolvido com base na Classificacao Internacional da Funcionalidade; dados coletados a partir de entrevista estruturada por profissionais de saude nos centros de saude do Alentejo. RESULTADOS: 30,7% dos idosos declaram-se analfabetos, 22,9% vivem sozinhos. As necessidades de alimentacao (18,7%), habitacao (19,2%) e saude (26,0%) nao estao satisfeitas. Funcoes de orientacao preservadas em 83,4%; 58% dos idosos referem uma intensidade de dor que requer cuidados; 73,3% dos idosos nao apresentam denticao funcional. Niveis de desempenho superior a 80% nas atividades de participacao: lavar-se (82,6%), atividades relacionadas ao processo de excrecao (92,2%), vestir, comer, beber (89%). CONCLUSAO: decrescimo progressivo da funcionalidade a medida que a idade avanca; todavia, esta preservada em grande parte as dimensoes ate cerca dos 75 anos.

Comparing double minimization and zigzag algorithms in Joint Regression Analysis: the complete case

Joint Regression Analysis is a widely used technique for cultivar comparison. For each cultivar a linear regression is adjusted on a non-observable regressor: the environmental index. This index measures, for each block, the corresponding productivity. When all cultivars are present in all the blocks in the field trials, the series of experiments is complete. To carry out the minimization of the sum of sums of squares of residuals in order to estimate the coefficients of the regressions and the environmental indexes an iterative algorithm, the zigzag algorithm, was introduced, see Mexia et al. [J.T. Mexia, L 2 environmental indexes, Biom. Lett. 36 (1999), pp. 137–143.]. This algorithm performs well, see e.g. Mexia et al. [Weighted linear joint regression analysis, Biom. Lett. 38 (2001), pp. 33–40.] and Mexia and Pereira [J.T. Mexia, D.G. Pereira, Joint regression analysis for winter rye cultivars using L 2 indexes, J. Colloquium Biometryczne 31 (2001), pp. 207–212.] but it has not been shown that it converges to the absolute minimum of the goal function. We present an alternative algorithm and show that, in the complete case, it converges to the absolute minimum. Through an example it is shown that the results obtained using both algorithms agree. We analyse the reason behind the agreement between both algorithms.

A comparison between joint regression analysis and the AMMI model: a case study with barley

Joint regression analysis (JRA) and additive main effects and multiplicative interaction (AMMI) models are compared in order to (i) access the ability of describing a genotype by environment interaction effects and (ii) evaluate the agreement between the winners of mega-environments obtained from the AMMI analysis and the genotypes in the upper contour of the JRA. An iterative algorithm is used to obtain the environmental indexes for JRA, and standard multiple comparison procedures are adapted for genotype comparison and selection. This study includes three data sets from a spring barley (Hordeum vulgare L.) breeding programme carried out between 2004 and 2006 in Czech Republic. The results from both techniques are integrated in order to advise plant breeders, farmers and agronomists for better genotype selection and prediction for new years and/or new environments.

Overview of Friedman’s Test and Post-hoc Analysis

When the null hypothesis of Friedman’s test is rejected, there is a wide variety of multiple comparisons that can be used to determine which treatments differ from each other. We will discuss the contexts where different multiple comparisons should be applied, when the population follows some discrete distributions commonly used to model count data in biological and ecological fields. Our simulation study shows that sign test is very conservative. Fisher’s LSD and Tukey’s HSD tests computed with ranks are the most liberal. Theoretical considerations are illustrated with data of the Azores Buzzard (Buteo buteo rothschildi) population from Azores, Portugal.

Avaliação da funcionalidade e necessidades de cuidados dos idosos

OBJETIVO: avaliar a funcionalidade dos idosos com base na Classificacao Internacional da Funcionalidade. METODOS: estudo transversal, descritivo; amostra aleatoria, estratificada, com 903 idosos; nivel de confianca 95%; margem de erro 2,5%. Questionario desenvolvido com base na Classificacao Internacional da Funcionalidade; dados coletados a partir de entrevista estruturada por profissionais de saude nos centros de saude do Alentejo. RESULTADOS: 30,7% dos idosos declaram-se analfabetos, 22,9% vivem sozinhos. As necessidades de alimentacao (18,7%), habitacao (19,2%) e saude (26,0%) nao estao satisfeitas. Funcoes de orientacao preservadas em 83,4%; 58% dos idosos referem uma intensidade de dor que requer cuidados; 73,3% dos idosos nao apresentam denticao funcional. Niveis de desempenho superior a 80% nas atividades de participacao: lavar-se (82,6%), atividades relacionadas ao processo de excrecao (92,2%), vestir, comer, beber (89%). CONCLUSAO: decrescimo progressivo da funcionalidade a medida que a idade avanca; todavia, esta preservada em grande parte as dimensoes ate cerca dos 75 anos.

Analyzing genotype-by-environment interaction using curvilinear regression

In the context of multi-environment trials, where a series of experiments is conducted across different environmental conditions, the analysis of the structure of genotype-by-environment interaction is an important topic. This paper presents a generalization of the joint regression analysis for the cases where the response (e.g. yield) is not linear across environments and can be written as a second (or higher) order polynomial or another non-linear function. After identifying the common form regression function for all genotypes, we propose a selection procedure based on the adaptation of two tests: (i) a test for parallelism of regression curves; and (ii) a test of coincidence for those regressions. When the hypothesis of parallelism is rejected, subgroups of genotypes where the responses are parallel (or coincident) should be identified. The use of the Scheffe multiple comparison method for regression coefficients in second-order polynomials allows to group the genotypes in two types of groups: one with upward-facing concavity (i.e. potential yield growth), and the other with downward-facing concavity (i.e. the yield approaches saturation). Theoretical results for genotype comparison and genotype selection are illustrated with an example of yield from a non-orthogonal series of experiments with winter rye (Secalecereale L.). We have deleted 10 % of that data at random to show that our meteorology is fully applicable to incomplete data sets, often observed in multi-environment trials.

Evaluación del funcionamiento y necesidades de cuidados de los ancianos

OBJETIVO: avaliar a funcionalidade dos idosos com base na Classificacao Internacional da Funcionalidade. METODOS: estudo transversal, descritivo; amostra aleatoria, estratificada, com 903 idosos; nivel de confianca 95%; margem de erro 2,5%. Questionario desenvolvido com base na Classificacao Internacional da Funcionalidade; dados coletados a partir de entrevista estruturada por profissionais de saude nos centros de saude do Alentejo. RESULTADOS: 30,7% dos idosos declaram-se analfabetos, 22,9% vivem sozinhos. As necessidades de alimentacao (18,7%), habitacao (19,2%) e saude (26,0%) nao estao satisfeitas. Funcoes de orientacao preservadas em 83,4%; 58% dos idosos referem uma intensidade de dor que requer cuidados; 73,3% dos idosos nao apresentam denticao funcional. Niveis de desempenho superior a 80% nas atividades de participacao: lavar-se (82,6%), atividades relacionadas ao processo de excrecao (92,2%), vestir, comer, beber (89%). CONCLUSAO: decrescimo progressivo da funcionalidade a medida que a idade avanca; todavia, esta preservada em grande parte as dimensoes ate cerca dos 75 anos.

Joint-Regression Analysis and Incorporation of Environmental Variables in Stochastic Frontier Production Function: An Application to Experimental Data of Winter Rye

This chapter joins the main properties of two specific regression techniques, joint-regression analysis (JRA) and stochastic frontier approach (SFA) in the analysis of experimental data sets from a breeding program of winter rye (Secale cereale L.), conducted in Poland, Research Center for Cultivar Testing de Slupia Wielka, over the period 1997–1998. With JRA, a meta-model, based on several linear regressions, had been estimated in order to analyze multilocation trials of winter rye production and to select the best cultivars (more productive) for a related stratum (locality/genotype). With SFA, another regression model had been investigated to predict production rankings of cultivars, through individual efficiency estimates. These measures resulted from a stochastic production frontier on experimental data of production and different climate conditions. Both techniques show similar dominant cultivars for the same environments.

Application of Selective F Tests in Joint Regression Analysis

Joint Regression Analysis (JRA) has been widely used to compare cultivars. In this technique a linear regression is adjusted per cultivar. The slope of each regression measures the ability of the corresponding cultivar to answer to variations in productivity. Recently, we are mainly interested in cultivars with better response to high fertility. To single out such cultivars, in the context of Joint Regression Analysis, selective F-tests are used to see if there is a cultivar with significantly larger slope.