Psychometrically relevant population differences may limit the transferability of research instruments between migrants and their source population and may contribute to a low performance of quantitative questionnaires. Based on a review of existing taxonomies, this book develops a comprehensive analytical framework of equivalence that can serve multiple purposes. It allows to examine psychometrically relevant population differences, it can assist in the re-adaptation of questionnaires and it is a valuable tool for cross-group comparative research. The application of the framework is illustrated through the examination of equivalence of the Revised Illness Perception Questionnaire (IPQ-R) between chronically ill Turks residing in Turkey and Turkish migrants residing in Germany.
The Example of Illness Perceptions
Patrick Brzoska and Oliver Razum
Researchers studying the health of migrants frequently use standard quantitative instruments to assess psychological constructs. Such instruments are often validated only in the respective source population of migrants. For example, when studying Turkish migrants in Germany, instruments validated in Turkey are applied. However, considerable differences in culture and language may have developed between migrants and their source population. These differences limit the validity and reliability of quantitative instruments, a problem that is often overlooked. Using the example of the Revised Illness Perception Questionnaire (IPQ-R), the authors demonstrate that instruments known to be valid and reliable in source populations may lead to biased results when applied to migrant populations.