Invent your own research

 On March 30, Nicholas Kristof had wrote   "Survey data indicates that married couples on average report more happiness, build more wealth, live longer and raise more successful children than single parents or cohabiting couples, though there are plenty of exceptions."  The most popular reader comment, with over 2000 likes, said
"I notice that you didn't talk about the research that shows differences in gender in marriage happiness levels.
    Marriage is generally GREAT for men, who report being far happier in marriage than being single.  Much research indicates the reverse is true for women.  Single women report being happier, in general, than married women are." 
Most of the other leading comments were along the same lines.  

Since the 1970s, the General Social Survey has asked whether "taken all together, how would you say things are these days."  41% of married women say that they are very happy, and 8% say they are "not too happy" (the rest chose "pretty happy"); among single (never married) women, 23% say they are very happy and 17% not too happy.  This is just one survey, but it's one that puts a lot of effort into selecting a representative sample and gets a high response rate, so it can be considered to be pretty definitive.  Of course, the difference in happiness between married and never-married women is not necessarily caused by marriage, but it's there.  

But maybe the difference is smaller for women--married women are somewhat happier than single women, but married men are a lot happier?  The figure shows the averages for married and never-married men and women over the years (higher numbers mean happier).  There's a lot of sampling variation, so I also show the smoothed averages.  The pattern seems similar for men and women.

The next figure shows the difference between married and never-married people among men and women:  

Up until about 2000, the difference was a little bigger for men, but since then it's been about equal.  

I looked to see if the gap varied by other characteristics--for example, education, race, political views.  To make a short story even shorter, I found nothing worth mentioning.  

In the course of doing this analysis, I noticed that the GSS had a question on whether you thought that married people were generally happier than unmarried people.  45% agreed (or strongly agreed), 24% disagreed (or strongly disagreed), and 32% chose "neither agree nor disagree."  There were some group differences in average views on this question:  men were more likely to agree than women; whites more likely to agree than blacks or people of other races; conservatives more likely to agree than liberals; married and widowed people more likely to agree than never-married, with divorced people least likely to agree.  Despite what is sometimes said about "elites," there was no discernible difference by education, and people in higher status occupations were more likely to agree.  The question was asked only four times, most recently in 2012, but it seems like the gender difference was growing:  the means for men were 3.6 in 1988, 3.43 in 1994, 3.47 in 2002, and 3.32 in 2012; the means for women were 3.50, 3.26, 3.17, and 2.97 (higher means more agreement)--that is, the gender difference went from .10 to .35.  There were also signs that the gender difference varied among groups--for example, agreement was particularly low among black women (20% agreed and 48% disagreed).