What is the primary purpose of the Bonferroni correction?

• A. To adjust for Type II error when performing multiple tests
• B. To control for Type I error when performing multiple tests
• C. To increase statistical power
• D. To estimate effect size

Answer: (B)

When you run many statistical tests, the chance of getting at least one false positive grows. The Bonferroni correction tackles this by adjusting the significance threshold downward for each test, typically by dividing the overall alpha level by the number of tests. This keeps the overall probability of making any Type I error across all tests at your chosen level. That's why this method is used: it controls false positives in multiple testing situations.

Because it tightens the criteria for significance, it tends to reduce statistical power and can increase the chance of missing real effects. It also doesn’t provide effect size estimates. So its primary purpose is to control for Type I error when performing multiple tests.