The consistency of retrospective and current status data on contraceptive use from a series of national fertility surveys carried out during the 1970s in Korea is investigated. Aggregate consistency is examined among random samples from the same cohort or cohorts of women interviewed in each survey. The results indicate that estimates of trends in contraceptive use from a retrospective history in one survey, or from cross-sectional estimates in a series of surveys, can each yield misleading findings. Data from the 1974 Korean National Fertility Survey (KNFS) appear to be more reliable than those from other surveys, possibly because an interval-by-interval contraceptive history was used, explicit definitions of contraceptive methods were given prior to taking the contraceptive history, and the KNFS involved longer interviewer training and, perhaps, less time pressure during interviews.
PIP: This report investigates the consistency of retrospective and current status data on contraceptive use from a series of national fertility surveys carried out during the 1970s in Korea. Aggregate consistency is examined among random samples from the same cohort or cohorts of women interviewed in each survey. The results indicate that estimates of trends in contraceptive use from a retrospective history in 1 survey, or from cross-sectional estimates in a series of surveys, can each yield misleading findings. Data from the 1974 Korean Fertility Survey (KNFS) appear more reliable than those from other surveys. This is possibly the result of 1) the use of an interval by interval contraceptive history; 2) presentation of explicit definitions of contraceptive methods prior to taking the contraceptive history; or 3) the KNFS involving longer interviewer training and perhaps less time pressure during interviews. The results clearly show that there are dangers inherent in estimating trends in contraceptive use. On the other hand, evidence from the 1974 survey indicates that contraceptive use data of reasonable quality can be collected in a retrospective history, given adequate questionnaire design and interviewer training and effort. The fact that the results indicate large intersurvey differences in the completeness of reporting of use stresses the importance of evaluating contraceptives use data before they are analyzed.