Читать книгу Improving Health Care Quality - Cecilia Fernanda Martinez - Страница 26

Many of the traditional statistical methods, such as hypothesis testing, have assumptions that must be satisfied for the conclusions to be valid. For example, the assumptions underlying the one sample t‐test are that the data are continuous and follow a Normal distribution and were obtained as a simple random sample. Always check the assumptions underlying a statistical method to avoid drawing an erroneous conclusion. For example, constructing a Normal probability plot or performing a Shapiro–Wilks test verifies normality. The degree to which each method is robust to deviations from the assumptions varies. When assumptions are violated, there are often other methods that can be applied. In the case where the normality assumption does not hold in a one sample t‐test, the Wilcoxon signed rank test is an alternative. Additional information on dealing with violations of assumptions can be found in Rosner (2015).