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Chi-square (2×2, Yates)

§2.1
Rev 4.6 · reviewed Feb 2026
Chi-square test (2×2, Yates)
Compares an outcome proportion between two groups. Fill the four highlighted cells; the margins compute themselves.
Source formula: Yates F. J R Stat Soc Suppl 1934;1:217–35.
Table. Outcome by group
Outcome +Outcome −Total
Group 1100
Group 2100
Total48152200
* Yates continuity correction applied. Pearson K. Philos Mag 1900;50:157–75. Yates F. J R Stat Soc Suppl 1934;1:217–35.
† Proportion CIs are Wilson score intervals. Wilson EB. J Am Stat Assoc 1927;22:209–12.
Group 1 proportion (95% CI)*
18.0% (11.7%–26.7%)
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Group 2 proportion (95% CI)*
30.0% (21.9%–39.6%)
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χ² (1 df, Yates)
3.32
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Two-sided p
0.069
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Group difference
12.0% absolute
Groups measured 18.0% vs 30.0% (p 0.069) — not statistically distinguishable in this sample.
With p = 0.069, this study does not show a statistically significant difference — which is not proof the groups are the same, only that this sample can't distinguish them.
Understand what this is measuring