Reasons for wage differential are multiple. As OneSTDV points out, female intelligence distributions are narrower than male distributions are. Consequently, there are more men than there are women floating around in the intelligence stratosphere. Further, men do a much better job keeping themselves up to snuff on current events than women do. Men's range of intellectual interests are wider than women's are and men do a better job than women do learning about subjects that increase their employment marketability, and companies are pressured into offering more generous benefits for those taking maternity leave than for those taking paternity leave. Women's interests are closer to home and to those living in it.
Additionally, in certain occupations--specifically those requiring a great deal of physical exertion--the bar is set higher for men than it is for women, even though members of both sexes are treated (and potentially compensated) as though they are of equal value to their organizations in these positions. Take the PT for military enlistees. To pass once graduated from basic training, men (aged 17-21) must be able to do the following:
- 42 push-ups
- 53 sit-ups
- Run the two-mile in under 15:54 or faster
Less is expected of female soldiers:
- 19 push-ups
- 53 sit-ups
- Run the two-mile in 18:54 or faster
Further, women tend to have less tenure in positions than men do because men are more likely to seek full-time employment than women are and because female participation in the labor force continued to climb through the seventies, eighties, and nineties. A 40 year old woman who started working for a company in 1998 is, ceteris paribus, not going to be making as much as a 40 year old man who started at the same company in 1988. Much of the celebrated reduction in the wage gap is a consequece of this trend. With the current recession hitting men harder than women, expect further attenuation of earnings variance in the coming years.
The GSS provides another source of evidence for this, in addition to shedding light on some other attitudinal and behavioral reasons men earn more than women do for doing putatively 'equal work'. The following table shows data for men and women on four questions concerning work behaviors and attitudes. For contemporary relevance, all responses are from 2002 onward:
|Mean number of years on the job||7.5||6.8|
|Working other than day shifts (nights, swing, etc)||31%||26%|
|Work overtime at least once a month||69%||57%|
|Main satisfaction in life comes from work||30%||25%|
|Want to work additional hours to earn more money||36%||28%|
On all of these aspects of work life, men tend to be more occupationally devoted than women are. They've been with their companies longer, are more willing to work overtime and on oddball schedules, and receive more satisfaction from their jobs than women do.
The differences are modest. That's generally the case when it comes to measuring gender variances on social attributes. In contrast, when racial groups are compared, they are much larger.
GSS variables used: JOBYEARS, WRKSCHED, MOREDAYS, WKTOPSAT, HRSMONEY, SEX(1)(2)