The PISA student population is defined using stringent criteria to ensure a high level of coverage and full comparability of the assessment across countries (OECD, 2009b). The quality of the indicator is thus high. Despite the fact that reading literacy measures a relatively narrow set of competencies, there is strong evidence that reading literacy is strongly correlated with other cognitive and non-cognitive measures tested by PISA (e.g. mathematics, sciences, IT skills, etc. - Finally, while this indicator covers only youth, cognitive skills at age 15 are strongly correlated with later educational outcomes and labour market performance (Juhn et a!.,