Comparing means
From Wikipedia, the free encyclopedia
The introduction to this article provides insufficient context for those unfamiliar with the subject. Please help improve the article with a good introductory style. |
The following tables provide guidance to the selection of the proper parametric or non-parametric tests for a given data set.
Contents |
[edit] Is there a difference ?
1 group | N ≥ 30 | One-sample t-test | ||
N < 30 | Normally distributed | One-sample t-test | ||
Not normal | Sign test | |||
2 groups | Independent | N ≥ 30 | t-test | |
N < 30 | Normally distributed | t-test | ||
Not normal | Mann-Whitney U or Wilcoxon signed-rank test | |||
Paired | N ≥ 30 | paired t-test | ||
N < 30 | Normally distributed | paired t-test | ||
Not normal | Wilcoxon signed-rank test | |||
3 or more groups | Independent | Normally distributed | 1 factor | One way anova |
≥ 2 factors | two or other anova | |||
Not normal | Kruskal-Wallis one-way analysis of variance by ranks | |||
Dependent | Normally distributed | Repeated measures anova | ||
Not normal | Friedman two-way analysis of variance by ranks |
1 group | np and n(1-p) ≥ 5 | z-approximation | |
np or n(1-p) < 5 | binominal | ||
2 groups | Independent | np < 5 | fisher exact test |
np ≥ 5 | chi-square test | ||
Paired | McNemar or Kappa | ||
3 or more groups | Independent | np < 5 | collapse categories for chi-square test |
np ≥ 5 | chi-square test | ||
Dependent | Cochran´s Q |
[edit] Sources
- Dawson-Saunders, Beth; Robert G. Gapp (1994). Basic & Clinical biostatistics. Lange medical book. ISBN 0-8385-0542-2.