Cain, Zhang, Yuan, in press) With such non-normal data, it is extremely difficulty to use an analytical formula to calculate power as in traditional
du-zhang-yuan-2017.pdf
Conclusions: We recommend the use of this sample size calculation approach for outcome data that are expected to be positively skewed and where a two group
s12874-017-0426-1.pdf
falsely suggest the data are skewed or even bimodal Similarly, if you have a large sample size (n > 200), the Anderson-Darling normality test can detect
Tips-and-Tricks-for-Analyzing-Non-Normal-Data-002.pdf
you can calculate sample size for most statistical tests Non-parametric data: does not fit a normal distribution; alternative and less powerful tests
sample_size_gpower_module.pdf
on the specific design, you can calculate sample size Non-parametric data: does not fit a normal distribution; alternative and less powerful tests
sample_size_r_module.pdf
With small sample size normality of a data cannot be quarantined In an example, it was shown that sample of 50 taken from normal distribution looked nonnormal
EJ1259038.pdf