elementary or low levels of qualifications, given their generally high levels of education. Considering the difference between immigrants who have attained their degree in their home country with those who have attained it in Denmark, Table 4 shows that 42% of immigrants with a Danish education are employed in jobs requiring high or medium level qualifications, whilst the share is 13% for those educated in their home country (and 37% for ethnic Danes).

Tables 5-8 cross-tabulate educational attainment and job skill level to provide a sense of the degree of job-to-education mismatch among native Danes, immigrants in general, immigrants with a Danish education, and immigrants with a foreign-acquired education, respectively. Table 6, for example, shows that among immigrants with a long higher education, 21% are employed in jobs requiring just elementary or a low level of qualifications. Among Danes with a long higher education (Table 5) only 4% are employed in such jobs. There are, however, large differences between the two groups of immigrants. While 44% of immigrants with a foreignacquired long higher education are employed in jobs requiring just elementary or a low level of qualifications, only 4% of immigrants with a Danish long higher education are in such a situation. Similar patterns are found for individuals with short and medium-length higher educations with the most striking differences again being between native Danes and immigrants with foreign credentials. The job-to-education match of immigrants with a Danish education tends to be more similar to that of native Danes. Calculating the column percentages (not shown in the tables), it is worth noting that among individuals employed in jobs that require only elementary qualifications, 22% of immigrants with foreign credentials have a higher level of education (short, medium or long). To compare, such a mismatch applies for only 3% of native Danes and 6% of immigrants with a Danish education employed in elementary jobs.

# **4. Empirical methods**

# **_4.1. Measuring overeducation_**

Measuring overeducation is by no means a straightforward exercise.<sup>16</sup> Indeed, this measurement issue is one of the most controversial aspects of the overeducation literature. Three different techniques to measure overeducation are typically used: job analysis (JA), realized matches (RM), and worker self-assessment (WA) (see e.g. Linsley 2005, Verhaest and Omey 2004, Battu and Sloane 2002). The JA approach is based on the assessment by professional job analysts of the education and training requirements for different occupations and compares this with the actual educational attainment of individual workers. In principle, this is an appealing approach because of its “explicit goal of objectivity, clear definitions and detailed measurement instructions”, yet in practice it runs into several problems (Hartog 2000 p.132). In particular, occupational categories in conventional data sets are typically quite broad, resulting in a great deal of heterogeneity in job requirements within the same occupational title.

> 16 Some researchers make a point of distinguishing between educational mismatch and skill mismatch. These two concepts are of course related, yet Allen and de Weert (2005) stress that educational mismatch is neither a necessary nor a sufficient condition for skill mismatch. Based on a survey performed in Spain, Germany, the Netherlands, UK and Japan, they find that the wage effects of educational mismatches are much stronger and more consistent across countries than the effects of skill mismatches.

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