Question

Compare and contrast two nonparametric tests performed in biostatistical studies. When do public health researchers use nonparametric tests? How do they compare with parametric tests?

Answer 1

Parametric test assume underlying statistical distributions in the data for example, students t-test for two independent samples is reliable only if each sample follows a normal distribution and if sample variances are homogeneous

Non parametric tests also called distribution-free tests because they don't assume that your data follow a specific distribution you have heard that you should use non parametric tests when your data don't meet the assumptions of the parametric test, especially the assumption about normally distributed data