A 2009 study sponsored by the US Department of Labor, which analysed about 50 studies on the gender pay gap, concluded that "The differences in raw wages may be almost entirely the result of the individual choices being made by both male and female workers."
There are observable differences in the attributes of men and women that account for most of the wage gap. Statistical analysis that includes those variables has produced results that collectively account for between 65.1 and 76.4 percent of a raw gender wage gap of 20.4 percent, and thereby leave an adjusted gender wage gap that is between 4.8 and 7.1 percent.[1]
http://www.consad.com/content/reports/Gender%20Wage%20Gap%20...
When it later talks about 'the gap' remaining after accounting for other variables. It means a smaller gap and it cites different studies. It just doesn't provide the 'after controlling for choices' value, only that one exists.
http://go.nationalpartnership.org/site/DocServer/wf.epd.fact...
It's not a national study, no, and Utah has been cited as being one of the top 5 states in the gender pay gap so this is admittedly higher than many other states. It also states that this gap remains at about the same amount (66 to 72 cents per dollar) regardless of industry, education level, or personal choices (eg, raising children or being married).