makes a strong argument that wages rather than actual earnings should be used because hours
worked during marriage are likely to differ from hours worked at the threat point.
All of these approaches, however, require that wage or income information be
available for both partners. This requirement effectively restricts the sample to dual earner
couples or to those who both contributed to earnings within the last year, often excluding
large numbers of more traditionally focused households (Couprie 2007; Geist 2005; Solberg
and Wong 1992; van Klaveren, van Praag, and van den Brink 2008). Such restrictions may
introduce a sample selection bias. While there has been little effort to address this problem,
one approach has been to work with potential rather than actual earnings (for example, Kan
2008).
Conditions in the marriage market may also influence power and hence θ. Chiappori,
Fortin, and LaCroix (2002) discuss marriage market conditions and divorce law
considerations as “distributional factors” that influence bargaining power but not preferences
or the budget constraint. The ratio of men to women in a market may be important because if
there are many men for every woman, then women will likely have more bargaining power
because they are relatively scarce. Grossbard and Amuedo-Dorantes (2007) demonstrate the
importance of sex ratios as a determinant of women’s labor force participation rates in the US.
Likewise the ease with which relationships can be ended and the rules employed to divide up
household resources in the event of a breakup may influence θ. For this reason, married
partners and cohabiting partners may allocate time in different ways. It is certainly more
„expensive’ to formally end a marriage than to end a cohabitation, particularly in the United
States where cohabitation is only marginally recognized by law. If these costs fall
disproportionately on the higher earner in the household, then his/her bargaining power may