Friedman test
The Friedman test is an extension of the Wilcoxon signed-rank test and the nonparametric analog of one-way repeated-measures. Friedman tests the null hypothesis that k related variables come from the same population. For each case, the k variables are ranked from 1 to k. The test statistic is based on these ranks.
- Example
- Does the public associate different amounts of prestige with a doctor, a lawyer, a police officer, and a teacher? Ten people are asked to rank these four occupations in order of prestige. Friedman's test indicates that the public does associate different amounts of prestige with these four professions.
- Statistics
- Mean, standard deviation, minimum, maximum, number of nonmissing cases, and quartiles. Tests: Friedman.
Data considerations
- Data
- Use numeric variables that can be ordered.
- Assumptions
- Nonparametric tests do not require assumptions about the shape of the underlying distribution. Use dependent, random samples.
Obtaining a Friedman test
This feature requires Statistics Base Edition.
- From the menus choose:
- Click Select variables under the Dependent variables section, select one or more numeric test variables, and then click OK.
- Optionally, expand the Additional settings menu and
click the following:
- Click Comparisons to specify options for multiple comparison tests.
- Click Options to specify the confidence interval, significance level, case basis for analysis, and user-missing values settings.
- Click Run analysis.
This procedure pastes NPTESTS command syntax.