Reliability study of reporting of days since last sexual intercourse in Matlab, Bangladesh

The accuracy of responses to a question on the frequency of sexual intercourse in the 4-week period prior to an interview is expected to be low. This paper examines the reliability of an alternative question: 'How many days since you last had sexual intercourse?'. This was a part of a larger longitudinal study of fertility dynamics in Matlab, Bangladesh. The response pairs of 61 women who were asked the same question by an interviewer and on the next day by a supervisor, were analysed. Refusals were more common among older women and among women who gave a response at the extremes of the distribution for the other interview. Of the pairs of two responses, 78% had a difference of 3 days or less. Further study and use of the question on days since last intercourse is recommended.