**Question:** Comparison of proportions can be made by:

A. Pairwise comparison
B. Chi-square test
C. Fisher's exact test
D. Odds ratio

**Correct Answer:** C. Fisher's exact test

**Core Concept:** Fisher's exact test is a statistical method used to compare proportions between two or more independent groups when the sample sizes are small or the expected cell count is less than 5 in any cell of the contingency table. This test is more powerful than the chi-square test when cell counts are low.

**Why the Correct Answer is Right:** Fisher's exact test is suitable for comparing proportions in scenarios where the assumptions of the chi-square test (e.g., large samples, expected cell count >5) are not met. In such cases, Fisher's exact test provides a more powerful test statistic, allowing for more accurate comparison of proportions between groups.

**Why Each Wrong Option is Incorrect:**

A. Pairwise comparison: This involves comparing two proportions directly, which may not account for the combined effect of multiple groups.

B. Chi-square test: This test assumes large sample sizes and expected cell counts >5, which may not be true in some situations, leading to incorrect results.

D. Odds ratio: This statistic compares the odds of an event occurring between two groups, which is different from comparing proportions.

**Clinical Pearl:** Fisher's exact test is crucial when dealing with small sample sizes or low expected cell counts in contingency tables, as it provides a more accurate comparison of proportions between groups. Understanding when to apply it is essential for reliable statistical analysis in medical research and clinical studies.