Nonparametric statistical methods provide alternatives to classical analyses without making the usual assumption that data come from a normal distribution (or any other specific distribution). STATGRAPHICS Centurion includes such methods in many of its statistical procedures. Typically, the nonparametric techniques are included as options in the procedures that implement the parametric techniques, rather than being lumped together in a separate menu.

Some of the nonparametric procedures included are:

1. One Sample Analysis - sign test and signed rank test for location.

2. Two Sample Comparison - Mann-Whitney (Wilcoxon) test and two-sample Kolmogorov-Smirnov test.

3. Oneway Analysis of Variance - Kruskal-Wallis and Friedman tests.

4. Multiple Variable Analysis - Spearman and Kendall rank correlation coefficients.

5. Simple Regression - minimum absolute deviation regression.

6. Life Tables - Kaplan-Meier estimation of survivor functions.

7. Life Data Regression - Cox proportional hazards models.

8. Distribution Fitting - chi-squared and one-sample Kolmogorov-Smirnov tests.

9. Run Charts - runs tests for non-random behavior.

10. Contingency Tables - Kendall's tau and other measures of association.