Table 1 Operationalization of the main variables of interest

Rational choice factors

Educational motivation: university entrance qualification (B + c * UM)

Benefit (B): ‘How favourable would you judge your prospects of getting a good job if you did the Abitur?’, 1 (very bad) → 5 (very good)

Importance of upward mobility (UM): Item 1 ‘How important is it to you that you have a similar or better school-leaving qualification than your parents’, Item 2: ‘How important is it to you to later have a similarly good or better job than your parents’, 1 (very unimportant) → 5 (very important)

Probability (c) of upward mobility: ‘What would be the prospects for a similarly good or better vocation than that of your parents if you did the Abitur?’, 1 (very bad) → 5 (very good)

Wave 2 (if missing wave 3)

Investment risk: university entrance qualification (C/p)

Costs (C): ‘As long as you go to school, you can hardly make your own money. Most of the things you need are paid for by your parents (e.g. school things, clothing). How hard would it be for your parents to pay these costs if you did the Abitur?’, 1 (very easy) → 5 (very difficult)

Expected probability (p): ‘Regardless of the kinds of qualifications you can earn at your current school, how likely is it that you could pass the Abitur?’, 1 (very unlikely) → 5 (very likely)

Wave 2 (if missing wave 3)

Social influence factors

Parental educational expectations as perceived by adolescents (% university)

Item: ‘And what kind of education would your parents like you to get after you have left school? My parents would like me to’, 1 = study, 0 = else (to do a vocational training, to do no vocational training at all, my parents have no opinion)

9th grade, wave 1

Share of friends with aspirations for university entrance qualification

Item: ‘How many people from your circle of friends intend to obtain the Abitur?’, 1 = none, 2 = almost none, 3 = less than half, 4 = about half, 5 = more than half, 6 = almost all, 7 = all

9th grade, wave 1 (if missing, wave 3)