Assuming iso-work is a fair description of behavior in many rich countries, it is natural to try to explain it as the outcome of market forces that differ across countries but present women and men within each country with similar economic choices. This is a difficult task. To start, economic theory would predict iso-work as a market outcome if men and women: (1) had the same preferences over work and leisure—or at least could be approximated by the same representative agent; (2) faced the same market wage, net of taxes and other costs of participation, and (3) had identical productivity in home production. To deviate from this set of implausible symmetry conditions and still obtain iso-work as an equilibrium outcome, additional restrictions on preferences, prices and endowments are necessary. For example, if goods produced at home are perfect substitutes for market goods, and the representative man and woman have identical Cobb–Douglas preferences over leisure (and no differential disutility from hours supplied in either type of work), then the combined supply of hours to market and home production is constant and identical across gender. Because these assumptions are hardly more plausible than the symmetric and symmetric-and-equal assumptions, iso-work as a market outcome seems more likely a coincidence than a central tendency across economies robustly predicted by theory.
The task becomes even more difficult when we try to explain deviations from iso-work in developing countries and their tendency to disappear as economies develop. Assuming substitution effects dominate income effects, economic theory predicts that a rise in women’s relative wage (i.e., a decline in the gender wage gap) will lead to more work in the market by women relative to men. The impact of this increase on the relative amount of home work should be in the opposite direction, so that the effect of a change in the gender gap on the relative amounts of total work is ambiguous. Unless, however, additional market work is offset one-for-one by reduced home work, a rise in the female relative wage should raise women’s relative total work.
To examine this possibility, we use estimates of the difference between the logarithms of the medians of the distributions of males’ and females’ wages produced by Polachek and Xiang (2009) for 19 of the 27 countries used here. The first two columns in Table 2 present least-squares estimates of equations describing female–male differences in market and total work across countries as functions of the gender wage gap. The results on market work are consistent with an upward-sloping relative supply curve of labor. The market work effect, however, dominates the household work effect, so that we find that the female–male gap in total work is also positively related to the female–male wage ratio.
These findings are not affected by the inclusion of real GDP per-capita, as the estimates in Columns (3) and (4) show, nor are they affected by adding the indicator for Catholic countries. That the GDP variable is only marginally statistically significant, whereas Fig. 2 suggested a strong negative relationship with a diminishing slope, arises from the exclusion of many of the poorer countries (for which relative wage data are unavailable). Despite the quality of the estimates, the equation in Column (6) describes below half of the variance in the gender difference in total work across countries. The difficulty is that in 14 of these 19 countries these differences are clustered within 5% of equality, while the gender wage gaps in these data range from 0.07 to 0.69. Something besides equality in relative wages or differences in per-capita incomes is causing the pervasive absence of gender differences in total work.
Bargaining, matching and imitation within couples
A different perspective on iso-work arises from the literature on household behavior (e.g., Lundberg and Pollak 1996). In this view, the gender wage gap reflects differences in bargaining power in the household, as it would be regardless of whether one views spouses’ behavior as described by a unitary or a collective model. By this criterion, we should expect to observe men working relatively less in total when female–male relative pay is lower, if preferences over leisure are normal.Footnote 5 The estimates in Table 2 imply the opposite result. Where one might infer that men have more bargaining power, as measured by relative wages, their total work is in fact greater.
A second possible explanation for some of these facts is that husbands and wives pay attention to each other’s labor and leisure, and gender equality obtains at the means in rich countries because most adult men and women are married. An explicit test of the notion that gender iso-work is generated by husbands and wives focusing on each other’s work effort as part of marriage comes from examining inter-household dispersion in the within-household gender total work gap using data on couples. This examination is not possible for the U.S. in 2003, so instead we use the much smaller 1985 U.S. Time Use Survey. We use averages over 3 days from the 2001/02 German data and over 2 days from the 1992 Australian survey.
Figures 3, 4 and 5 show frequency distributions of within-household differences between the average daily total work of wives and husbands in the U.S., Australia and Germany. While the distributions are symmetric around means of zero, the implied dispersion is large. Regressions within each country of the wife’s total work time on the husband’s explain only 9% of the variation in the U.S., 29% of the variation in Australia and 35% in Germany. We do find evidence of complementarity of spouses’ total work (and thus of leisure), but most of the dispersion in intra-household differences in total work remains.Footnote 6 This evidence is inconsistent with the assertion that the iso-work phenomenon stems from the alignment of behavior within a couple, perhaps not surprising given the demonstration by Cigno (2009) that iso-work could result from non-cooperative equilibria, which are less likely within marriage.Footnote 7
Another possible coordination device that we explore here is a social norm for leisure that generates a form of interdependent utility among agents and serves as a focal point for the determination of total work. Social norms have been increasingly incorporated into economic models, and they provide important additional insights and modifications into how we view markets as operating (see Fernández 2010, for a discussion). In our context, peer pressure leading to a desire to conform to a common social norm for time allocation mutes market incentives and weakens the impact of individual tastes. As a result, time use becomes more similar across individuals.Footnote 8 If the social norm is strong enough to drive agents to conform fully, we obtain the iso-work result suggested by the data.Footnote 9
While there are many variations on the theme, models of social norms have the following common feature. Absent a social norm, consumers maximize utility given a standard budget constraint. Common behavior—as an average of that of members of a given and possibly endogenously determined group—conditions utility, so equilibrium enforces consistency of the individual’s maximizing behavior with the group outcome. Deviations from the norm are costly.
A simple model of social norms is not sufficient to rationalize our observations. The empirical difficulty is that iso-work coexists with significant within-gender (and more generally within-group) heterogeneity of leisure. This is inconsistent with a simple single-norm account, because, as the penalty for deviating increases, the labor supply of each individual converges to a common, gender-neutral norm regardless of the wage.Footnote 10 While a strong norm bridges the gap between male and female leisure, it also suppresses any within-gender heterogeneity of leisure, which is a central feature of the data.
One way to avoid this feature is to allow multiple local social norms, unrelated to gender.Footnote 11 Suppose each gender is stratified into social clusters that are defined by relative position in the wage distribution. For instance, males and females above their gender’s median wage may share a common leisure norm, and there is another leisure norm below the median wage. Agents could just as well be clustered according to the color of their eyes, the month in which they are born, or the neighborhood where they live. The crucial assumption is that the clusters are defined by gender-neutral characteristics.Footnote 12 In such models the greater the number of clusters or interacting groups, the more likely that iso-work can obtain.
The findings presented in Section 2 make it clear that total work does vary across countries, region and over time. Since one might rationalize iso-work by social norms by arguing that they serve as a coordination device between male and female total work, we must also explain how norms can vary. This is most simply done by endogenizing the norm.
A social norm theory of leisure can produce the negative relation between female–male differences in total work and GDP per-capita in various ways. The first relies on the link between economic development and increased gender neutrality of social reference groups. A model of social clusters can account for the reduction in the female–male total work difference as GDP per-capita grows, provided economic growth is positively correlated with the adoption of gender-neutral reference groups. Suppose that at low income levels there are two leisure reference groups: one for men, and one for women. This might be due to tastes for discrimination, for example, which are correlated with income level. Then, trivially, iso-work does not hold. If gender-oriented social clusters are replaced by gender-neutral reference groups as income rises (e.g., at quantiles of income distributions), development will be associated with convergence of the total work difference.
A second variant assumes that the cost of deviating from a social norm is positively related to the wage. Consider the simple one-norm model when people are harassed for deviating from the norm. Perhaps instead of suffering the direct utility loss envisaged above, deviants lose time fending off their critics, mending their reputations, or battling inner guilt feelings at the cost of time available for work or leisure. At a low wage or level of development, the weight on the norm is low, so that the intrinsic optimum is the main determinant of leisure. At a high wage or development level, the social norm becomes the sole determinant of optimal leisure. As the wage—the value of time—increases, so does the cost of deviating from the norm, resulting in a smaller deviation.
A final possibility is that there is a social stigma attached to female participation in market activities. Goldin (1995) assumes that blue-collar, but not white-collar work by a woman entails a fixed utility loss. Imagine a simpler scenario in which any positive female market activity is stigmatized, and there is no social norm beyond this stigma. If a woman works in the market, her utility is diminished by a fixed penalty associated with the stigma, while conformity to stereotyped behavior yields positive additional utility. Staying home is optimal as long as the utility differential exceeds the valuation of market participation.Footnote 13 Development and the concomitant rise in wages reduce the impact of gender stereotypes on behavior. In that respect, development makes men and women behave, ceteris paribus, in increasingly similar ways.Footnote 14