Patterns of response and non-response in longitudinal survey of Oyo community, Oyo state, Nigeria

A B ST R A C T There is widespread concern that the cumulative effects of the non-response that is bound to affect any long-running longitudinal study will lead to mistaken inferences about change. We focused this work on the Longitudinal Survey of Oyo town covering the existing fifteen (15) Enumeration Areas to show the patterns of response and non-response. The Surveys started in 2008 and a two-stage stratified random sampling scheme was used in selecting 750 households. Household heads were interviewed in five waves (waves 1, 2, 3, 4 and 5). We used an interviewer-administered questionnaire to collect data on the demographic characteristics of the respondents. The Response rates for waves 1 through 5 were 77.86%, 82%, 81.33%, 82% and 80.67% respectively while the non-response rates were 22.14%, 18%, 18.67%, 18%, and 19.33% respectively. The average number of visit ranges from a minimum of 1.2 in Kosobo to a maximum of 4 in Ladigbolu. The average duration of the household interview ranges between a minimum of 7.7 minutes in Monbolaje and a maximum of 18 minutes in Asipa. Finally, fieldwork lasts on average of 11.8 hour in Asipa, but only 6.6 hours in Monbolaje. The most common interview mode is the Pencil-And-Paper (face-to-face) Interview. New entry is linked to eligibility, whereas monotone attrition is mainly due to migration. Occasional responses are due to absences while that of nonresponses are due to out of scope and lack of cooperation.