“…Among these, analyses by Mincer (1963), Bean and Wood (1974), and Gardner (1973) utilized individual level data while studies by Heer and Boynton (1970), Gardner (1972), DeTray (1973), and Cain and Weininger (1973) employed areal data (areal units in the latter four studies were counties, states, counties, and SMSA's, respectively). Almost all of these studies used male income as the indicator of capability to purchase children and female income or wage level as the indicator of cost of children.…”