Surveying ethnic minorities: the impact of survey design on data quality

The demand for information about ethnic minorities remains at a constantly high level. An important reason is that national and regional administrations need information about the socioeconomic position and the degree of integration of ethnic minorities in order to implement better policies. Official registers can provide a part of this information, but no data is available in the registers on topics like religious beliefs, identity and integration. As a consequence, surveys remain necessary. It is very important that the results of these surveys should be of a high quality and that they should be fit for answering the research questions, in other words that the results of such surveys can be trusted.

Obtaining accurate survey data about ethnic minorities is not easy. Ethnic minorities are usually underrepresented in surveys. Furthermore, it is not certain that people that do take part in surveys are representative of the group one is interested in. Do, for instance, only people with high education take part, or people with a good job, or people who were born in the Netherlands? To ensure that everybody can participate, one needs a tailor-made approach, such as translating the questionnaires and using interviewers with the same ethnic background as the intended respondents. This tailor-made approach can lead to higher response, but does a translated questionnaire still measure the same things as the original? In order to be able to trust the results, survey data needs to be of good quality, different groups need to be readily comparable – in spite of linguistic differences – and the data should also, preferably, be available quickly. How quickly one wishes to obtain the results and the overall budget also determine the upper limit of the data quality: to get a high response, for instance, one needs a longer fieldwork period.

The relation between the survey design and the quality of the survey data related to non-Western minorities in the Netherlands is the main focus of this dissertation. With respect to data quality, the focus was on two aspects of data quality that seemed the most relevant in this context: accuracy and comparability. For accuracy, we studied mainly 1) representation, or how well the population under study is represented by the respondents of a survey, and 2) measurement, meaning how the manner in which data has been collected among respondents may affect the answers they provide. With respect to comparability, the focus has been on the comparability of data collected from different minority groups. Attention has also been paid in the dissertation to the costs of surveys among non-Western minorities.