An APL procedure to estimate genotype by environment interaction when two environments are considered

Genotype by environment interaction (GEI) is a relevant topicin many fields of applied biology. Normal parametric approachesfollowing analysis of variance are not suitable when large differencesbetween error variances within environments are present. Weillustrate an APL program following Yamada's approach to estimateGEIs and ancillary statistics when two environments are considered.The choice of APL environment is based on its value as a usefultool in algorithm implementation and problem-solving. Its useis suggested in biological applications where matrix algebrais involved and an understanding of the computing complexityof problems is generally not required.