SigmaAnalytics & Tech
E6PythonAdvancedAbout 150 min to complete

Non-parametric Tests

The t-tests and ANOVA of the last two notebooks assume your data is roughly normal with equal variances. Real data — skewed incomes, ordinal survey ratings, tiny samples, outlier-riddled measurements — often breaks those assumptions.

Notebook

About 150 minutes to complete

Enrol to read the notebook and download it to run.

What this module covers

The t-tests and ANOVA of the last two notebooks assume your data is roughly normal with equal variances. Real data — skewed incomes, ordinal survey ratings, tiny samples, outlier-riddled measurements — often breaks those assumptions.

By the end of it

  • Explain when and why to prefer non-parametric tests, and the power trade-off involved
  • Run and interpret the rank-based alternatives:
  • Use Spearman correlation and Fisher's exact test as non-parametric tools
  • Report appropriate effect sizes (rank-biserial, ε²)
  • Run permutation and bootstrap tests with SciPy — flexible methods that assume almost nothing
  • Perform post-hoc comparisons after Kruskal–Wallis with multiplicity correction