The PIAAC survey provides a measure of the numeracy and literacy skills. One obvious concern in the context of the present analysis is to what extent these measures actually reflect skills acquired while in education, given that skills are likely to depreciate with age, and might be complemented by those accumulated at work. These concerns are addressed both empirically and based on previous results suggesting that PIAAC skills largely reflect those accumulated while studying (see Annex 3 for a discussion).