Analysis of Nonnegative Observations using Gamma Model with 2 Factors (ANOGaM-2): Theory, Method and Applications with Real-life Data (including R code)
Two-factor ANOVA is widely used in experimental studies but relies on additivity, normality, independence, and homoscedasticity. These assumptions are often violated for nonnegative, positively skewed observations. Although Box--Cox-type transformations are commonly used, they may reduce interpretability and require a...