Analysis of longitudinal data in experiments with sugar of cane / Análise de dados longitudinais em experimentos com cana-de-açúcar
AUTOR(ES)
Edjane Gonçalves de Freitas
DATA DE PUBLICAÇÃO
2008
RESUMO
This work has been dealt with situation in which observations of productivity of sugar of cane (TCH) were taken in the same unit experimental in different condition of assessments (years). The response profiles average of 48 genotypes of sugar of cane were evaluated in two experiments: Experiment 1 and Experiment 2, for three and five years respectively, both with the randomized complete block design. This type of planning produces a form of relationship between the observations made in the same unit experimental therefore requires other assumptions, in addition to the usual, so that analysis is correct and the test results valid. To that inferences on the means of productivity are valid and safe it is necessary that the model of covariance matrix of the data is appropriate. Therefore, were evaluated three alternatives for analysis of longitudinal data (repeated measures over time), the univariate model as the planning of the split-plot on time which imposes strong restrictions on variances - covariances matrix, the multivariate model, which uses a non-structured variances - covariances matrix and mixed model, which they are enable the selection of a matrix that best represents the data. However, it was found that there was no difference between the results of tests for the different methodologies. But it is interesting the continuity of the study in relation to mixed model, because due to its flexibility and accuracy will be possible to obtain more reliable estimates of the variance components and predict the genotypic values, which ultimately could provide a prediction of production of a future harvest for a given genotype.
ASSUNTO(S)
cana-de-açúcar mixed model. medidas repetidas univariate model multivariate model repeated measures over time análise de dados longitudinais análise multivariada cane of sugar
