Comparing Different Approaches for Sampling Portuguese Migrants and TheirDescendants in Germany

Sampling procedures are a factor in determining a survey’s data quality. Whereas many easy-to-use procedures exist for the general population, approaches for sampling small, hidden and/or hard-to-reach populations are more difficult. Many individuals with a migration background or ethnic minorities are part of these challenging populations, which hinders our possibilities to study for example their experiences or political attitudes and beliefs more closely. Relying on name-based procedures (onomastic classification) for pre-qualifying person addresses is by most considered the gold standard at the moment. Such a procedure is not always feasible as it is cost-intensive and relies on a large number of personal addresses in the pre-qualifying sample in order to identify a sufficient number of members of small groups that can serve as the gross sample. Furthermore, it has been shown that using onomastic classifications increases the risk of systematically missing well-integrated individuals. Currently, several other approaches have been tried such as WebRDS or using social media ads but so far, they have not been tested systematically against each other. Our research aims to close this research gap. For this research project, we focus on the group of Portuguese migrants and their children (i.e., 1st and 2nd generation) in Germany which has not been studies before. While the population of Portuguese Germans is relatively small (under 200,000 individuals) and geographically concentrated in the German states of Nord Rhein-Westphalia and Baden-Württemberg, the population varies greatly with respect to age, length-of-residence in Germany, reason for migrating, degree of integration, and other important characteristics.In addition to the name-based approach, we test the efficacy and representativeness of three other common methods used to sample ethnic minorities and other hard-to-reach groups: (web) respondent-driven sampling, social media-based convenience sampling, and center (time/location) sampling, to determine which performs better. We evaluate these methods based on their cost-effectiveness in providing a representative sample of Portuguese Germans participating for the DeZIM.panel. We compare representativeness of the samples to the German Microcensus and cost-effectiveness to a probability-proportionate-to-size sample of Germans of all ethnicities. Our paper will provide an overview of our implementation of each method, including the strengths and weakness of each; our evaluation criteria; and preliminary results