In survival analysis using the Kaplan-Meier method, what is the correct handling of 'censored' observations?
- A They are excluded from the analysis entirely
- B They contribute to the risk set until the time of censoring and are then removed ✓
- C They are counted as events at the time of censoring
- D They are replaced by the mean survival time of the cohort
Correct answer: B. They contribute to the risk set until the time of censoring and are then removed
Explanation
Censored observations represent individuals who did not experience the event during follow-up (lost to follow-up, withdrew, or study ended). In the Kaplan-Meier method they are included in the risk set up to the last known time, then withdrawn; this prevents their removal from biasing the survival estimate. Treating them as events or excluding them would distort the survival curve.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.