Uso de modelo misto para a anÃlise de dados longitudinais de um experimento com bovinos em lactaÃÃo / Mixed model to analyse experimental longitudinal data with dairy cattle

AUTOR(ES)

Stephania Maria Teixeira Furtado

DATA DE PUBLICAÇÃO

2009

RESUMO

Longitudinal data offer information about global and individual variation over time. The size of ordered collection and the relationship between the observations is a distinctive feature of longitudinal data. This work aimed to study longitudinal data from dairy cattle experiment, conducted to compare two treatments consisted of supplementation differentiated (ration until 60 and ration until 120 days postpartum). Each treatment was applied to eight cows, which were grouped according with previous production, genetic composition, weight, age and order of birth. The tests were performed using the software SAS by considering adjustment of two models, one by considering the block effects as random (mixed model) and another with fixed components (split-plot in time). Also, it was adjusted Wood nonlinear model, which were compared by models identity test. It was found that there was difference between results for both methodologies and the mixed model appropriate to analyse this lactation data.

ASSUNTO(S)

covariance structure longitudinal data estatistica estrutura de covariÃncia mixed model dados longitudinais modelo misto

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