Which error occurs when no pathology is noted when it is actually present?

• A. Type II Error
• B. Type I Error
• C. False Positive
• D. False Negative

Answer: (A)

The main idea is failing to detect something that is actually there. This is a Type II error, also called a false negative: the test concludes there is no pathology, but pathology truly exists. In statistical terms, you fail to reject the null hypothesis when the alternative is true. This contrasts with a false positive, where a test indicates disease when none is present (a Type I error). Clinically, a Type II error means you miss a real condition, which can delay treatment; improving sensitivity reduces the chance of this error, since higher sensitivity means fewer missed cases. The probability of a Type II error is beta, and power equals 1 minus beta.