Which type of error is most important to minimize in disease detection when missing a case is critical?

• A. Type I error (false positive)
• B. Type III error
• C. Both Type I and Type II errors equally problematic
• D. Type II error (false negative)

Answer: (D)

When the priority is not missing a true case, the key is to minimize false negatives. A false negative happens when someone who actually has the disease is told they are disease-free. That corresponds to a Type II error, and in screening terms it means you want high sensitivity because sensitivity is the ability to detect those who are sick. If you raise sensitivity, you catch more true cases and reduce the number slipping through as undetected.

In this scenario, a false positive—labeling a healthy person as diseased—causes unnecessary follow-up and anxiety, but it doesn’t carry the same risk of ongoing transmission or disease progression as missing a real case. Therefore, prioritizing sensitivity to curb Type II errors is most appropriate. Type III error isn’t the standard concern in this context, and claiming that both error types are equally problematic ignores the asymmetry of costs when a missed case has critical consequences.