“…This makes a decrease from a total of 146,120 available students to a final working sample composed by 123,979 students, nested 10 The index of socioeconomic status in PISA is built combining an indicator for home possessions, (HOMEPOS), the higher parental occupation (HISEI) and the higher parental education expressed in years of schooling (PARED). 11 Following the literature pointing out the importance of early childhood education and demonstrating its positive impact on later student achievement (Barnett, 1995;Berlinski, Galiani, & Gertler, 2009;Brilli, Del Boca, & Monfardini, 2013). 12 From the OECD PISA Technical report: "School responsibility for curriculum and assessment: an index of the relative level of responsibility of school staff in issues relating to curriculum and assessment (RESPCURR) was computed from four items measuring the school principal's report concerning who had responsibility for curriculum and assessment ("Establishing student assessment policies", "Choosing which textbooks are used", "Determining course content", and "Deciding which courses are offered").…”