Add it to the list: women are better than men at stewarding their retirement accounts, at least if we define better as "more likely to be in the game."

Earlier studies have already indicated that women outperform as hedge fund chiefs and as stock traders, but now a study from Vanguard shows they do better in important respects with their 401(k) accounts too.

Crucially, not only are women saving at higher rates within given income bands, they are 14 percent more likely overall to participate in workplace savings plans.

Compared with men, women trade less, about a third less among the more than 3.6 million plan participants for which Vanguard directly provides record-keeping.

Women also save more, at least as a percent of their incomes, which are lower. When you control for wages, age, tenure on the job and other factors, women 401(k) savers defer salary into plans at a rate 3 percent higher than men.

Interestingly, that's true up and down the earnings scale, including at lower wage levels.

Women are more likely to use target date plans, which shift allocations gradually ahead of a planned retirement date. Those plans have their shortcomings, but they are usually far better than simply making your own trading decisions. Women overall are more likely to turn over their asset allocation decision to a professional, and as a result tend to have more sound portfolios.

Men also are more likely to hold shares in their employers in retirement accounts. Employees are already making a substantial bet on their company by working there. From a diversification and risk management point of view owning too much of an employer's stock can be a mistake. None of this should be surprising, particularly the propensity to not trade needlessly. A survey by hedge fund research company HFR released this year showed that hedge funds run by women racked up 59 percent total returns since 2007, against 37 percent for the average fund.

It also tends to rhyme with a 2014 report from Merrill Lynch based on a survey of their investors showing that women were more likely to say that they know less than average about finance and investing. Given how poorly the typical investor does on his or her own, that kind of humility is a good thing.

Far be it from me to say why women are less overconfident, but men, if they'd like to be better investors, might want to take note.

James Saft is a Reuters columnist.