Best index of contraceptive efficacy is
Pearl index
Chandelers index
Quetlet index
Broca index
Pearl index is defined as the number of failures per 100 woman years of exposure (HWY) Failure rate per Hundred Women Years = Total accidental pregnancies X 1200/ Total months of exposure Reference : Park&;s textbook of preventive and social medicine, 23rd edition, Page no: 510
Demography and family planning