Why do we use nonparametric tests? Describe a psychological research situation or scenario that would use a non-parametric test. Why would the non-parametric test be used?
I thought it was rather peculiar as we were learning about hypothesis testing that the assumption of a normal distribution was always there. I know that the text has said repeatedly that normal distributions are, for lack of a better word, the norm when dealing with statistics. I am glad to learn that modern statistics has come up with a way to handle non-normal distribution. I am sure that they do show up from time to time. It appears that nonparametric tests are most widely used in situations where data has a ranking rather than a numerical ratio-scale. Because of the wide range of uses for the nonparametric test they are considered more robust than parametric tests, which depend largely on preset limits (i.e. normal distributions).
Aron, A., Aron, E., & Coups, E. (2006). Statistics for psychology (4th ed.). Upper Saddle River, NJ: Pearson/Allyn Bacon.