Low response rates present a common problem in epidemiological surveys. People with foreign background might show lower response rates, due to factors such as language problems. Different strategies to increase response rates have been used and their effect differs.
In a recently published study at the International Journal of Public Health, the authors studied the response rates of potential study participants in Germany according to foreign versus German background; furthermore, they examined what effects different recruitment strategies had on the response rates.
In Germany, more than 19% of the population has a foreign background. People with Turkish and people with Eastern European background with German ancestors (called “Aussiedler”) form the largest groups. This study used data from feasibility studies in planning a National Cohort study (NaKo) and data from 1,235 participants and 11 different study centers were analyzed. Some of the incentives used to increase response rates were reimbursement of the travel expenses, media campaigns, home visits, provision of the results of the medical examinations and money.
The authors found that the proportion of recruited foreign individuals was 17%, which was significantly lower than in the sampling frame (23%). This difference was higher among people with Turkish background and smaller among ethnic Germans from the Former Soviet Union and other foreign background groups.
Performing a media campaign had the strongest positive effect on the overall response as well as on the response of individuals with foreign background. Generally, people were more likely to participate in a study if they expect personal benefit.