Independent variables
I used six control variables to assess whether the effect of classroom diversity is not
spurious. I first discuss the individual-level control variables as the classroom-level
conditions, including diversity, are based on these variables. The individual-level
variables are: (1) gender [0 - girl; 1 - boy]; (2) social background (scale with six values
based on the item ‘number of books at home’); (3) civic competence (a ready-made
composite measure based on the results of a civic knowledge and skills test); (4)
ethnoracial identity [0 - ethnic majority; 1 - ethnic minority] (based on the “which best
describes you” item). The importance of each of these conditions in shaping different
civic outcomes has been amply demonstrated in the literature and need not be repeated
here.
Regrettably, the item on which the last-named variable is based was worded
differently in the three states. While it tapped subjective identification in England and
Sweden, it queried an objective marker of identity in Germany. In England the question
was indeed “which best describes you?” with the answer categories ‘White’ (N=2593);
‘Black Caribbean’, ‘Black African’, ‘Black Other’ (100); ‘Indian’, ‘Pakistani’,
‘Bangladeshi’, ‘Chinese’ (156) and ‘Other’ (123). In Sweden the item was phrased as
“Do you most often feel you are ...” with the categories ‘Swedish’ (2386); ‘Finnish’ (54);
‘Arab’, ‘Iranian’, ‘Kurdish’ and ‘Turkish’ (178); ‘Bosnian’, ‘Croatian’, ‘Serb’,
‘Albanian’, ‘Polish’ (62); ‘Something else, which is.’ (43). In contrast, youngsters in
Germany were asked “What is your state citizenship (Staatsangehoerigkeit)?” and could
choose from ‘German’ (3383); ‘Italian’ (25); ‘Turkish’ (94) and ‘Other’ (117). I created
the ethnoracial identity variable by labelling those who reported belonging to the
dominant group (White, German, Swedish) as the ‘ethnic majority’ and those who
affiliated with other groups as the ‘ethnic minority’.
Nonetheless, the “which best describes you” item is the only item that can be used
to create a measure of classroom ethnic diversity - the well-known ethnic
fractionalization index (EFI). This index takes both the number of ethnic affiliations and
the size of each group into account. It has values ranging from zero (total homogeneity)
to one (all students in the classroom belong to different ethnic groups). Higher values