Power analysis — chi-square
Sample size or power for chi-square goodness-of-fit and contingency tests with effect size w (.1 small, .3 medium, .5 large).
Menu: Analyze → Power Analysis → Chi-square…
When should I use it?
- Planning a crosstab study.
What are the assumptions?
- df = (rows − 1)(columns − 1) for a contingency table.
How do I run it in StatLab?
- Give w, df, α and the target power (or N).
How do I read the output?
| Output | Meaning |
|---|---|
| Total sample size / Actual power | Result of the search. |
Worked example
On the practice survey dataset (File → Sample dataset), this command — which the dialog's Paste button also produces — runs the procedure:
PROC pwChisq /mode=n /w=0.3 /df=1 /alpha=0.05 /power=0.8.
Output tables: Power — χ² tests: goodness-of-fit / contingency (a priori).
How would I report it in APA style?
A sample of 88 gives power .804 to detect the stated effect at α = .050.
Computed by StatLab's validated procedure code when this page was built. The example only illustrates the steps; choose variables that fit your own research question.
What are common mistakes?
- Using the number of cells instead of df.