Alessandro Dal

Transformação box-cox em experimentos com pimentão em ambiente protegido

Box-cox transformation in experiments with green pepper in protected environments The major purpose of vegetable crops production systems is the profitable and economically viable yield of marketable products. Numerous field experiments with vegetable crops are carried out to determine biomass production of marketable and nonmarketable variables. However, these variables possess the particular characteristic related to their presence or absence at harvest time. Absent variables, represented by zero values, generate variability and affect variance analyses. This research deals with the search of applicable transformations for variables studied in green pepper field experiments carried out in protected environments attempting to stabilize the variability resulting from the presence of zero values in multiple harvests. The analysis was based on experiments with the green pepper crop carried out in summer-fall or winter-spring season, using an adaptation of the Box-Cox transformation family found in Yamamura (1999). Despite the reduction in variability and normal errors, observed in all experiments, the use of the method was not efficient to make the variances homocedastic. For experiments with green pepper, assessing the phytomass and number of fruits, the inverse fourth root transformation is indicated.