Representativeness of the sample

Overall non-response rates appeared to be high for all study groups raising doubts about statistical representativeness of the survey data. Fortunately, some characteristics of non-respondents were available in the sampled population register records (i.e. age, sex, place of residence, marital status). Analyses revealed that differences between respondents and non-respondents with respect to these characteristics were either absent or slight.

City level

Response rates in Amsterdam and Rotterdam were rather similar, on average 30.1 per cent (Table 1.1). The Moroccan study group had the lowest response rates of 25.1 per cent in Amsterdam and 24.2 per cent in Rotterdam, while the comparison groups had the highest response rates in both cities, namely 40.1 per cent in Amsterdam and 29.2 per cent in Rotterdam. These response rates were lower than the outcomes of the 2004 Permanent Living Conditions Survey (POLS), in which non-Western second-generation respondents in Amsterdam had a response rate of 33 per cent and those of Dutch decent 41 per cent. For Rotterdam this was 52 and 53 per cent, respectively. Yet, given the lack of origin specificity, it is not possible to pinpoint the response rate of specific second-generation groups.

The characteristics of respondents in Amsterdam, for 18-35 year old TIES respondents and 15-35 year old city residents, are displayed in Table 1.4. The number of women appeared to be slightly overrepresented in the TIES sample compared to the city population. Furthermore, while second generation Turks and Moroccans in the TIES sample tend to be older than the city population, for the comparison group the opposite seems true. It should be noted here that the first age group of the city population refers to 15 to 19 year old persons, while for the sample of TIES respondents it refers to 18-19 year old persons only.

Table 1.5 shows the characteristics of respondents and residents in Rotterdam. Unlike Amsterdam, in Rotterdam, men are only slightly overrepresented. The sampled Turkish and Moroccan TIES respondents are somewhat older than the city population from which they were sampled, while members of the comparison group appear to be somewhat older.