The classical two-sample t-test works well for the normally distributed data or data with large sample size. The tcfu() and tt() tests implemented in this package provide better type I error control with more accurate power when testing the equality of two-sample means for skewed populations having unequal variances. The approximation is especially useful when the sample sizes are moderate. The tcfu() uses the Cornish-Fisher expansion to achieve a better approximation to the true percentiles. The tt() provides transformations of the Welch's t-statistic so that the sampling distribution become more symmetric. For more technical details, please refer to Zhang (2019) <http://hdl.handle.net/2097/40235>.
The function 'tcfu()' implements the Cornish-Fisher based two-sample test (TCFU) and 'tt()' implements the transformation based two-sample test (TT). The function 't_edgeworth()' provides the Edgeworth expansion for cumulative distribution function for the Welch's t-statistic, and 't_cornish_fisher()' provides the Cornish-Fisher expansion for the percentiles. The functions 'adjust_power()' and 'pauc()' provide power adjustment for simulation studies so that the actual size of the tests are within the significance level.
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.