**
**## Nonparametric statistical tests

__Nonparametric__ statistical
tests are used instead of the **parametric** tests we have considered thus
far (e.g. *t*-test; *F*-test), when:**
**

The following are some common nonparametric tests:
__Chi square__: c^{2}

1. used to analyze __nominal__ data

2. compares observed frequencies to frequencies that
would be expected under the null hypothesis

__
__### Mann-Whitney U

1. compares two independent groups on a DV measure
with rank-ordered (ordinal) data

2. nonparametric equivalent to a t-test

__
__### Wilcoxon matched-pairs test

1. used to compare two correlated groups on a DV measured
with rank-ordered (ordinal) data

2. nonparametric equivalent to a t-test for correlated
samples

__
__### Kruskal-Wallis test

1. used to compare two or more independent groups on
a DV.with rank-ordered (ordinal) data

2. nonparametric alternative to one-way ANOVA