After accounting for student and school-level socio-economic status, students who had attended early childhood education for one year or more scored an average of 25 points higher in the PISA science assessment compared to those who had not. However, there are limits to the interpretation of this finding, as the proportion of those who had attended less than one year of early childhood education (ISCED 0) represents on average across OECD countries of only 8% of all 15-year-olds, and is relatively low' in several OECD countries (Tables 5.1 and 5.2 on the web only). For instance, before accounting for student and school-level socio-economic status, students who had attended early childhood education for three years or more scored an average of 40 points higher in the PISA science assessment compared to those who had attended ECEC for less titan one year.