Chi-Square Calculator for 2×2 Contingency Table
This calculator performs a chi-square test for association in a 2×2 contingency table, providing full details of the calculation including expected frequencies and chi-square components.
When to Use
Use the chi-square test when you want to determine whether there is a significant association between two categorical variables, each with two levels (hence the 2×2 table).
Requirements
- Two categorical variables, each with 2 categories
- Independent observations
- Expected frequency in each cell should be at least 5 (for reliable results)
Null Hypothesis
H₀: There is no association between the two variables (they are independent).
Formula
χ² = Σ((O - E)² / E)
Where O is the observed frequency and E is the expected frequency for each cell.
Expected Frequencies
E = (Row Total × Column Total) / Grand Total
