Reliability and Validity of Household Disaster Preparedness Index (HDPI)

Introduction: The preparedness of families for the disasters can set auspicious grounds for the preparedness of the whole society. In Iran health system, Household Disaster Preparedness Index (HDPI) that is composed of 15 items is applied for assessing the household preparedness in disasters. This study was conducted to investigate the reliability and validity of this index. Methods: In order to investigate the HDPI reliability, we two methods, namely internal consistency and stability determination, are. In order to investigate HDPI validity, we examined the face validity, content validity and construct validity. To do so, besides interviewing with the experts and family heads, 200 families were selected based on multistage cluster sampling method from amongst a study population that included the families in all the counties in Isfahan Province. Use has been made in content validity investigation of both qualitative and quantitative methods; and, in investigating the construct validity, exploratory factor analysis was the method of choice. Results: The amount of HDPI internal consistency was calculated 0.786 which is in an acceptable range. HDPI stability, as well, was computed 0.98 using the test-retest method which is also in an optimal level. Therefore, it can be stated that HDPI enjoys the required reliability. Investigation of HDPI face validity indicated that the families have problems in perceiving some of the items of this index. The experts presented suggestions for improving the HDPI content validity following the qualitative investigation of the content validity. In the investigation of the content validity ratio (CVR), all the items, except the ones numbered 1, 3 and 4 were in an acceptable range; however, the investigation of the content validity index (CVI) indicated that only the validity of the items numbered 12 and 13 was acceptable in terms of all the three scales of relevancy, clarity and simplicity. To determine the construct validity, we used exploratory factor analysis to extract five factors (subscales), namely reduction of vulnerability, planning for disasters, family empowerment, procurement of resources for disasters and specialized programs. The internal consistency of these subscales indicated that only the internal consistencies of the first and the second factors were in an acceptable range. Conclusion: The present study revealed that although HDPI was a reliable measure, it did not enjoy the required validity for assessing the household preparedness in disasters.