The 3 main types of Chi-square tests are:
- Chi-square goodness-of-fit test: used to compare the distribution of a categorical variable (with more than 2 levels) to a hypothetical distribution.
- Chi-square homogeneity test: used to test whether 2 groups (coming from 2 different samples) have the same distribution regarding a certain categorical variable.
- Chi-square independence test: used to evaluate if 2 categorical variables are related or independent of each other.
Information that should be reported
Reporting the use of a Chi-square test
No matter which version of the Chi-square test you use, the following information should be reported in the METHODS section of your research paper:
- the assumptions of the Chi-square test (the observations should be drawn independently from the population, and most levels of the categorical variable (>80%) must contain at least 5 observations)
- the type of Chi-square test used (i.e. goodness-of-fit, homogeneity, or independence test)
- the objective of the test
- the threshold for statistical significance, generally set at 0.05.
Reporting the results of a Chi-square test
The following should be reported in the RESULTS section of your research paper:
- the results of the Chi-square test:
- the value of the Chi-square statistic
- the degrees of freedom
- and the p-value
- the consequence/interpretation of these results
The links below provide detailed information with examples on how to report each type of Chi-square test: