For example, Ferreira and Gignoux (2014, p. 232), in a study of inequality of educational opportunity using PISA data, argue that: "Because 15 year-olds may conceivably affect the choice of school they attend, the class they are assigned to, and thus the teachers they interact with, all school characteristic variables, for example, are included in [effort]." This is a bold leap to make, even when considering children of this age. The extent to which (a) children realistically have choices about this matter, and (b) are empowered to make these types of decisions independently of parents and other adults will vary according to context. Additionally, our analysis includes children from 8 years of age upwards, and the above argument is even less likely to apply to younger age groups.