This study investigates the quality of the National Family Health Survey-4 data on contraceptive use by estimating investigator-induced bias. An outlier-bound approach was used to detect investigator bias, and contraceptive use was re-estimated adjusting for the bias in six study states. The findings suggest investigator bias at two levels: over-reporting of women as “never users” of contraception and a tendency to report sterilised women as current non-users and as cases of hysterectomy. Re-estimation of contraceptive use confirmed a declining trend in contraceptive prevalence in four study states. While the effect of the bias was moderate at the state level, it can potentially distort district-level estimates to a great extent.
