Research finds that Fox News increases Republican vote shares and makes Republican politicians more partisan.[1][73][74][75] A 2007 study, using the introduction of Fox News into local markets (1996–2000) as an instrumental variable, found that in the 2000 presidential election "Republicans gained 0.4 to 0.7 percentage points in the towns that broadcast Fox News", suggesting "Fox News convinced 3 to 28 percent of its viewers to vote Republican, depending on the audience measure".[42] These results were confirmed by a 2015 study.[75] A 2014 study, using the same instrumental variable, found congressional "representatives become less supportive of President Clinton in districts where Fox News begins broadcasting than similar representatives in similar districts where Fox News was not broadcast."[74] A 2017 study, using channel positions as an instrumental variable, found "Fox News increases Republican vote shares by 0.3 points among viewers induced into watching 2.5 additional minutes per week by variation in position."[73] Another 2014 paper found Fox News viewing increased Republican vote shares among voters who identified as Republican or independent.[76]