Many statistical methods require the assumption of normally distributed data. This assumption often does not hold. In addition, some sample sizes are so small that you can’t verify if the distribution is normal. Nonparametric statistical methods do not make too many assumptions about the population from which the sample is drawn. SPC for Excel contains the following nonparametric techniques:
- One sample sign test
- One sample Wilcoxon signed rank test
- Mann-Whitney test for two samples
- Kruskal-Wallis test for multiple samples
Select “NonParametric” from the “Statistical Tools” panel in the SPC for Excel ribbon.
Select the option you wish to use.
Use the links above to access the help pages for the nonparametric tests.