Instant Reaction Polls Show Narrow Obama Advantage in Second Debate Polling data is often very noisy -- so it makes my job easier on those rare occasions when there is some agreement. Scientific polls conducted after Tuesday night's presidential debate in New York give a modest edge to President Obama. A CBS News/Knowledge networks poll of undecided voters who watched the debate found 37 percent giving an advantage to Mr. Obama, 30 percent favoring Mitt Romney and 33 percent calling the debate a tie. That represents a narrower lead for Mr. Obama than Mr. Romney had after the first debate in Denver, when a similar poll gave Mr. Romney a 46-22 edge. A CNN poll of registered voters who watched the debate -- not just undecided voters, as in the CBS News survey -- also gave the debate to Mr. Obama by a seven-point margin, 46 percent to 39 percent. Mr. Romney had won by a much larger margin, 67 percent to 25 percent, in CNN's poll after the first debate. Mr. Obama may have benefited in the CNN poll from diminished expectations: 73 percent of voters in the poll said he performed better than they expected, against just 10 percent who said he did worse. Two other polls gave Mr. Obama a somewhat clearer advantage. A Battleground poll of likely voters in swing states who watched the debate had him winning 53-38. An online poll by Google Consumer Surveys gave Mr. Obama a 48 percent to 31 percent edge among registered voters. There were also two scientific surveys about the debate conducted among voters in particular states. A Public Policy Polling survey of Colorado voters who watched the debate found 48 percent declaring Mr. Obama the winner, and 44 percent for Mr. Romney. Mr. Obama's advantage was clearer in the poll among independent voters, who gave him a 58-36 edge. However, the candidates were roughly tied when Public Policy Polling asked them how the debate swayed their vote, with 37 percent saying the debate made them more likely to vote for Mr. Obama, with 36 percent for Mr. Romney. Finally, a poll of California voters who watched the debate, conducted by SurveyUSA, found a 56-32 edge for Mr. Obama. It is no surprise that Mr. Obama won a poll of California voters, and the poll showed a tie, 44-44, among independents in California. Still, a similar poll of California voters by SurveyUSA had given an edge to Mr. Romney after the first debate. How much will the debate move the head-to-head polls between Mr. Romney and Mr. Obama? Actually, the instant-reaction polls may not be very much help in answering that question. The relationship between the quick-reaction polls and their eventual effect on the horse-race polls has historically been very modest, and has sometimes even run in the opposite direction of what the initial polls suggested. Debates sometimes look different in the rear-view mirror, depending on news media coverage, YouTube and cable news highlights, word of mouth, and subsequent developments on the campaign trail. Another complication is that it is possible -- although by no means guaranteed -- that there will be some reversion to the mean because of the first presidential debate, meaning that Mr. Obama will benefit from memories of Denver fading as much as any new ones that were forged in New York. But if you want my best guess: Throughout this election cycle, you would have done very well by predicting that the polls would eventually settle in at an overall lead for Mr. Obama of about two percentage points. Whenever his lead has been larger than that, it has come back to earth. But Mr. Obama has also rebounded at moments when the polls seemed to suggest an even closer race. A two-point lead for Mr. Obama is also close to what might be suggested by recent economic data as well as Mr. Obama's net approval ratings. The FiveThirtyEight forecast had Mr. Obama as a 64.8 percent favorite to win the Electoral College in advance of the debate, but it will take several days for it to incorporate any of its effects. Prediction markets, which had nearly identical odds to the FiveThirtyEight model in advance of the debate, had Mr. Obama's stock improving slightly over the course of the evening and put his odds at about 67 percent as of midnight on Wednesday.