METHODOLOGIC ISSUES Validation of a home safety questionnaire used in a randomised controlled trial

Objective: To measure the validity of self reported safety practices from a questionnaire, completed by families participating in a home safety randomised controlled trial. Methods: The postal questionnaire was used to measure secondary outcomes in a randomised controlled trial. The answers to 26 questions that could be assessed by observation were checked by a home visit. Families were invited to take part in a “home safety check”; they were not told that the visit was part of a validation study. At the time of the visit the researcher was blind to the self reports in the questionnaires. Results: Sixty four questionnaires were validated by visits to 64 households. Percentage agreement ranged from 58% to 100%. Sensitivity was high (68% or above) for most safety practices. The positive predictive value was also high for most safety practices (78% or above for 15 of the 16 practices). Conclusions: This study found a fairly high degree of consistency between self reported data and actual observations. The findings from this relatively small study need confirmation from larger studies.