Students who reported that they expect to work as college, university, higher education or pre-primary teachers, or as pre-primary or primary associate teachers are excluded. First, the question on career expectations has more missing values than other questions in PISA. Second, the predictive value of students' reports on their future career can differ across countries, because of differences in the degree to which students are required to make choices at an early age to enter specific careers, and the existence of flexible pathways in the education system and labour market.