What are the most commonly used parametric and non-parametric tests?
The most common parametric tests, those that assume something about the population of the D.V. (such as it being normally distributed), are the t-test, ANOVA, and Pearsons r. The t-test is used when there are only two groups, such as a 50mg and 100mg group. ANOVA, which stands for analysis of variance, is used when there are three or more groups, such as a 50mg, 100mg, and a 200mg group. The t-test yields a t value, but ANOVA yields an F value. Both the t-test and the ANOVA are used to test for differences between or among discrete groups. Pearsons r, however, is a correlation test used to look for associations between two continuous variables, such as height and weight or GPA and IQ. The most common non-parametric tests are the Chi-square and Spearmans r. Just like Pearsons r, Spearmans r is a correlation test, but it is used when you have rank data (first, second, third, etc.) instead of continuous data. The Chi-square test is used when you only have frequency or count data, such as
