Comparing two testing procedures in unbalanced two-way ANOVA models under heteroscedasticity‎: Approximate degree of freedom and parametric bootstrap approach

ýThe classic F-test is usually used for testing the effects of factors in homoscedastic two-way ANOVA modelsý. ýHoweverý, ýthe assumption of equal cell variances is usually violated in practiceý. ýIn recent yearsý, ýseveral test procedures have been proposed for testing the effects of factorsý. ýIn this paperý, ýthe two methods that are approximate degree of freedom (ADF) and parametric bootstrap (PB) approaches are evaluated in terms of type one error and powerý. ýThe simulation results show that these two methods have satisfactory performance in terms of type one error and their power is very close to each other approximatelyý. ýHoweverý, ýthe ADF method is very easy to implement in comparison with PB appreach which is simulation-based method and consequently time consumingý.