Using the EXCEL spreadsheet to compute the HC$-bases bootstrap estimate (estimate 2.3) of Ng and Wilcox (2010)
The spreadsheet on the previous page uses the recommended approach of Ng and Wilcox (2010) using their model 2.3 which they found controls for type I error when assumptions underlying regression analysis are relaxed. In particular it evaluates the t-statistic for the x by group interaction term.