Selected policies, institutions, and environmental factors, on the other hand, have a clear impact on education attainment. In particular, family background and teacher quality have been identified as important explanatory variables for student achievement. School autonomy and emphasis on assessing student performance are likely to raise education attainment, while teacher unions’ influence may have a negative impact. The effect of other factors on education attainment is ambiguous; these include the impact of class size, decentralization, and the relative importance of public and private education
