This document provides a flow chart for selecting popular statistical tests based on characteristics of the data. It asks a series of questions to determine the appropriate univariate or multivariable test for difference, correlation, or time to event outcomes. Based on the number of groups, sample size, type of outcome, and whether the data is paired or independent, different tests are considered valid including t-tests, ANOVA, regression, and non-parametric alternatives. The flow chart is intended to help researchers select the right statistical analysis for their medical research data.

1. Flow-chart for popularly used statistical tests
Q1,Univariate
/Mutivariable
Q2,
Difference
/Correlation
Q3,
Paired / related
Q６, No. of
groups
Q７,sample
size
Valid Tests
2 Student's t-test
＞2 One-way ANOVA
2 Mann-Whitney U test
＞2 Kruskal-Wallis H test
2 ＜20 Fisher's exact test
≧2 ≧20 Chi-square test
Log-Rank test（Kaplan-Meier plot）
2 Paied-t test
＞2 Repeated measured ANOVA
Mixed effect Regression
2 Wilcoxon signed-rank test
＞2 Friedman test
2 McNemar's test
Pearson's correlation （r）
Spearman's correlation （rs）
2 Spearman/Kappa (Agrreement）
Linear Regression
Linear Regression ＊
Ordered Logistic Regression
(2 levels) Binary Logistic Regression
(＞2) Multinomial Logistic Regression
Cox Proportional Hazard Regression
Linear Mixed Effect Regression
Linear Mixed Effect Regression ＊
Generalized Estimation Equation (GEE)
Generalized Estimation Equation (GEE)
＊Transform outcome variables for normalizing residuals
Created based on Publishing Your Medical Research Paper, by Daniel Byrne, Williams and Wilkins (1998)
Q4, Q5
Type of outcome (Normality)
Univariate
Difference
Independent
(un-paired)
Continuous （Normal）
Continuous （Non-normal）/ Ordered
categorical
Nominal
Time to Event
Dependent
(paired)
Continuous （Normal）
Continuous （Non-normal）/ Ordered
categorical
Nominal
Correlation
Continuous （Normal）
Continuous （Non-normal）/ordered
Nominal (2 levels)
Multivariable
Independent
(un-paired)
Continuous （Normal residuals）
Continuous （Non-normal residuals）
Ordered categorical
Nominal
Time to Event
Dependent
(paired)
Continuous （Normal residuals）
Continuous （Non-normal residuals）
Ordered categorical
Nominal (2 levels)