Biostatistics Knowledge Center

Making Categories Interpretable in Regression: References, Contrasts and Interactions

Understand how reference groups, ordinal coding, dummy variables and interactions determine regression interpretation.

8 min

Assessing Distributional Assumptions Beyond a Single Normality Test

Do not base normality decisions on one p value. Combine Shapiro–Wilk, Q–Q plots, residual diagnostics, sample size and robust methods.

Rank-Based Analysis Map for Independent, Paired and Repeated Data

A practical guide to choosing and interpreting Mann–Whitney, Wilcoxon, Kruskal–Wallis and Friedman tests without common misconceptions.

Scientific Decisions After p>0.05: Uncertainty, Confidence Intervals and Next Steps

A p value above 0.05 does not prove that there is no effect. Learn how to interpret effect sizes, confidence intervals, precision and study limitations.

Which Statistical Test Should You Use in Your Thesis? Complete Decision Guide

A practical decision-making guide to choosing the correct statistical test for your research based on data types, assumptions, and study design.

6/14/2026