When do I use chi-square and when correlation?

Chi-square is for categorical variables (yes/no, program, location). Correlation is for numeric or ordinal variables (scores, age, scales).

Yes: it matches the “Pearson Chi-Square” in SPSS crosstabs. This calculator doesn’t apply Yates’ correction to 2 × 2 tables.

For example: “There was a relationship between gender and preference, χ²(2, N = 100) = 15.80, p < .001, Cramér’s V = .40”. The calculator gives you that sentence with your data.

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Chi-square calculator

Use it to find out whether two categorical variables are related, for example gender and preference, or education level and satisfaction. Paste the frequency table (how many people fall in each combination) from Excel. Row and column names are detected automatically.

Paste your frequency table

Confidence level

The calculation runs in your browser. We don’t store what you type.

How it’s calculated

For each cell, the expected frequency if there were no relationship is: row total × column total / grand total.

χ² = Σ (observed − expected)² / expected. Degrees of freedom are (rows − 1) × (columns − 1).

The p-value comes from the chi-square distribution. Cramér’s V = √(χ² / (n × (min(rows, columns) − 1))) measures how strong the relationship is, from 0 to 1.

How to read the result

If p is below 0.05 (at 95% confidence), the variables are related: the distribution of one changes with the other.
A low p doesn’t mean the relationship is strong. Look at Cramér’s V for that: around 0.1 is weak, 0.3 moderate and 0.5 or more strong.
The test needs expected frequencies that aren’t too small. If more than 20% of cells have an expected value under 5, merge categories or use Fisher’s exact test.
Use counts, not percentages. Pasting percentages gives a wrong result.

Frequently asked questions

When do I use chi-square and when correlation?: Chi-square is for categorical variables (yes/no, program, location). Correlation is for numeric or ordinal variables (scores, age, scales).
Does it match SPSS?: Yes: it matches the “Pearson Chi-Square” in SPSS crosstabs. This calculator doesn’t apply Yates’ correction to 2 × 2 tables.
How do I report it?: For example: “There was a relationship between gender and preference, χ²(2, N = 100) = 15.80, p < .001, Cramér’s V = .40”. The calculator gives you that sentence with your data.

Is it for your thesis?See the step-by-step guide to running your thesis survey: sample, questionnaire, consent, pilot test and analysis.Thesis surveys

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