Health status and disability comparisons between CATI calendar and conventional questionnaire instruments

In comparison to conventional questionnaires, calendar interviews produce higher quality retrospective reports of factual information. This study sought to examine whether calendar interviews would also be advantageous in collecting retrospective reports of subjective assessment information. Respondents in a panel study were randomly assigned to either a calendar or conventional questionnaire method; both methods asked for retrospective reports on years in which disability was present and annual health status since young childhood. Panel data served as a source of validation for the retrospective reports. Both methods tended to underreport the number of years disabled and yielded mean levels of better annual health status in comparison to the panel reports. Calendar interviews demonstrated higher quality retrospective reports for disability in yielding a significantly stronger correlation in the frequency of years being disabled and in providing a greater number of years of higher annual correspondence with the panel data in comparison to the conventional questionnaire. Calendar interviews also demonstrated the ability to preserve the slope of change associated with aging as seen in the panel data, whereas the conventional questionnaire led to a significantly shallower slope of change. This latter finding could not be explained by the presence of an acquiescence bias.