Sample size and power of the study
IBS
Because there are no previous articles that address the overlapping effects of IBS and SxD on QOL using the SF-36 and IBS-QOL as main outcomes in the same population, we decided to recruit consecutive women as the first approach. In a post hoc analysis (StatMate 2 for Windows, version 2.00), we found a beta power greater than 80% (with alpha < 0.05) on the size effect of the main variables (domains and total summaries of the SF-36 and IBS-QOL questionnaires), so we conclude that the sample size was sufficient to obtain statistical validity (Additional File 