Guess what the majority of physical therapists (PTs) will be doing beginning December 2? According to a recent article in The Washington Post, that's when female PTs start working for free for the rest of the year while their male counterparts continue to get paid. And that disparity is actually a bit smaller than the one faced by most women in the workforce.

The Post article, published on October 26, examines the issue of gender pay gaps by way of establishing "work-for-free" dates in multiple professions—the date after which average wage disparities equate to the lower earning group (almost always women) working without pay for the remainder of the year. On a national level, according to the article, women's salaries are approximately 80% of what men receive, a gap that translates into 10 weeks of work without pay for women. Put into calendar form, that means that when averaged across professions, women began working for free on October 14.

The physical therapy profession fares better than the national average, with an estimated work-for-free date of December 2 for women. That correlates with an average hourly pay difference of $37.23 an hour for male PTs versus $34.33 per hour for female PTs, according to the article. Data for the report were derived from a study by IPUMS, a census and survey research organization that specializes in microdata.

The December 2 disparity date for physical therapists is the same as for elementary and middle school teachers. That date is better than the work-for-free date for physicians and surgeons (September 8) and dentists (October 19) but slightly worse than for registered nurses (December 6) and social workers (December 19).

The article includes graphics, potential causes, and an exploration of various theories that attempt to explain the gap. Those theories include the idea that women tend to choose lower paying jobs ("sort of," the article states), that they choose to work part-time (that's not always by choice, according to the Post), and that younger, more educated women don't experience a wage gap (they do).

"What this all hints to is that the causes of the gender gap are many and more nuanced than just individual choices or corporate discrimination," writes author Xaquin G.V. "However you slice the data, the gap is there."