Using a new twins sample, presents new estimates of schooling returns and "ability" bias and tests that bias's significance. Ability bias may exist even if ability's genetically-endowed component does not affect schooling decisions directly when correlated with other family characteristics (like income) that do affect schooling. (19…

Lower birth weight babies have worse outcomes, both short-run in terms of one year mortality rates and longer run in terms of educational attainment and earnings. However, recent research has called into question whether birth weight itself is important or whether it simply reflects other hard-to-measure characteristics. By applying within twin…

There is an extensive theoretical literature that postulates a trade off between child quantity and quality within a family. However, there is little causal evidence that speaks to this theory. Using a rich dataset on the entire population of Norway over an extended period of time, we examine the effects of family size and birth order on the…