Assumption and Data Transformation. Assumption of Anova. The error terms are randomly, independently, and normally distributed The variance of different samples are homogeneous Variances and means of different samples are not correlated The main effects are additive.
1. Data may consist of measurement on an ordinal or a nominal scale
2. Data may not satisfy at least one of the four requirements
1. It is recommended to use non-parametric data analysis
2. It is recommended to transform the data before analysis