Small percentage differences may not seem like much, but women's coverage is also highly concentrated in only a few events. Studies from as far back as the 1980s have found that media coverage of female athletes heavily focuses on "feminine" or "socially acceptable" sports, such as tennis or golf, and the UNC study found similar patterns in the Beijing summer games. Of all the primetime women’s coverage, 60 percent was dedicated to events considered feminine or acceptable by previous research: gymnastics, swimming, and diving. If you include beach volleyball, whose popularity is widely considered to be driven in part by its sex appeal, the number rises to 75 percent. And if you also consider any sport that requires female athletes to compete the equivalent to a bathing suit, that number rises to more than 97 percent.

Elsewhere, the study notes that while American women have been successful medalists in "big three" sports—basketball, soccer, and softball—their coverage of those sports declined steadily after 1999 and disappeared from the schedule entirely in 2008.

Why does this matter? "The paucity of reporting has reinforced the stereotypical dominance of male athletes, making female athletes at best marginal and at worst, nearly invisible," the authors write. They also cite several studies from the United Kingdom that find young girls who become active in sports struggle with pre-conceived ideas and expectations about femininity even as, in countries like the U.S., the number of girls competing in school athletics has grown exponentially since the 1970s.

But don't blame NBC, the researchers say. Blame society:

It is important to remember that a network’s primary concern is to deliver audiences to advertisers, and consequently it is likely to maximize audience sizes by putting the most popular sports events during prime time. It is not the contention of the authors that NBC is intentionally marginalizing any athletes. Instead, the network appears to be responding to the general public’s interest level in various sports, which was, in turn, influenced by social attitudes about femininity … A decision to spend more airtime on socially ‘‘unacceptable’’ sports may go a long way to making it ‘‘acceptable.’’ Based on the network’s ratings and profit success from the Beijing Games, however, there seems to be little incentive for NBC to change its approach when covering the 2012 Olympics in London.

The researchers noted some signs of progress, however: Contrary to their hypothesis, in power sports that especially relied on strength and bulk, which were not extensively covered, women's events received most of the coverage.

1996-2006: "All Three Winter Olympics Favored Men … By Significant Margins"

The discrepancies the UNC researchers noted would naturally seem to lend themselves to the summer Olympics, which has a greater range of events, completely different outfits, more exposed skin, and more instances where the athletic prowess and ideas about femininity come into contact. "It is interesting to note that all of the sports in which women received the majority of the coverage involved the wearing of swimsuits or leotards," Billings, who co-authored the study about the 2002 Olympics, wrote in a different study about all the Olympic Games between 1996 and 2006 that was published in a 2008 volume of Television & New Media.