This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Demography and family planning, Subject name: Social & Preventive Medicine
Best index for measuring contraceptive efficacy is 
Select and explain. 
A. Pearl index, B. Life-table analysis, C. Chandler's index, D. Quetlet index
B: Life-table analysis
Answer: B: Life-table analysis 
Explanation: Life table analysis : Calculates a failure rate for each month of use Cumulative failure rate can then compare methods of any specific length of exposure Women who leave a study for any reason other than unintended pregnancy are removed from analysis, contributing their exposure until the time of exit Reference : Park&;s textbook of preventive and social medicine, 23rd edition, Page no: 510