Family Size and Child Achievement

Using data from the British National Childhood Development Study, this paper examines the quality–quantity trade-off in fertility in multiple measures of child achievement. The results exhibit three characteristics: (1) Family-size effects appear very early in child development – as early as age two; (2) the effects are found in a broad array of achievement measures: labor market, cognitive, physical, and social; and (3) by age 16, the effects of family size stop growing (and what little evidence there is of change after that is not consistently in one direction). The paper argues that these results are inconsistent with preference-based explanations of the trade-off and point to some family-resource constraint. However, the relevant constraint appears more likely to be temporal than financial.