Intercoder-reliability for coding occupations according to ISCO-88 and the validity of socio-economic status

Indicators of social background belong to the standard set of instruments for empirical research in education. Construction of valid ranking scales and category systems for social background depends on a differentiated surveying of the occupation and vocational activity of parents. Coding such details using standard procedures is a complex process. This contribution investigates the intercoder-reliability of occupational codes according to ISCO-88 and the indicators for socio-economic status (ISEI) based on these codes using a random sample of 300 graduates surveyed on the occupation of their father and mother. To this aim, we compared a double-coding by professional coders and a double-coding by the research team. The results show a match of around 50 percent between the two coding groups. The validity of the index of socio-economic status based on the data was, however, very good. The correlation between ISEI-values based on the coding from the different coders was very high. The predication of family background did not vary between the coding of the different coding groups.