Early polls and focus groups suggest Hillary Clinton won the debate

It will be a few more days before we get methodologically rigorous polls measuring how the electorate felt about the first presidential debate. The indicators we have so far are necessarily incomplete and limited — they’re focus groups of tiny, hand-picked samples of undecided voters, polls of people who watched the debate rather than the electorate at large, and plain punditry.

Still, what we have so far points toward a Hillary Clinton victory.

We’ve got:

• A poll of debate watchers by CNN/ORC, which found that 62 percent thought Clinton won and 27 percent thought Trump did. CNN’s David Chalian emphasized on air that the sample was 10 points more Democratic than in a typical poll, but that’s still a strong win for Clinton.
• A poll of debate watchers by Public Policy Polling, which found that 51 percent thought Clinton won and 40 percent thought Trump won.
• A focus group of 20 undecided Florida voters by CNN found that 18 of them thought Clinton won.
• And a focus group of Pennsylvania voters by GOP pollster Frank Luntz overwhelmingly thought Clinton had won. Libby Nelson has more details about that here.

Furthermore, and potentially even more important, pundits in the media are converging on the narrative that Clinton won and Trump lost. This initial evidence will confirm those spot judgments, and that could matter. As I wrote earlier this month, political science research indicates that media judgments about who “won” a debate could help influence voters’ perceptions of who won.

A good debate for Clinton might move the polls — but not necessarily

Hillary Clinton has been sliding in the polls over the past few weeks, and the race has grown uncomfortably close for Democrats who were expecting a landslide just over a month ago.

So it’s certainly possible that Clinton will gain a few points in the polls from her debate performance, if the broader electorate agrees (or becomes convinced) that she won. After all, that’s what appeared to happen with Mitt Romney, who got a bump of a few points in public polling after he was judged to have won the first debate in 2012.

But there are a few reasons to be cautious about assuming this will be the case.

First of all, voters are perfectly able to conclude that one candidate “won” the debate without necessarily being won over to his or her side. That’s just common sense. After all, many supporters of Barack Obama concluded that he lost that debate with Romney, but they didn’t abandon him in droves — Romney just got a few points closer.

Second, as John Sides has written, the vast majority of people who watch these debates have already made up their minds. “The debates tend to attract viewers who have an abiding interest in politics and are mostly party loyalists,” Sides wrote. So it’s not clear what conclusions lower-information swing voters, who are less likely to have watched, will reach about what happened.

Third, polls after certain events can be affected by a phenomenon called differential non-response rates, as Jeff Stein explained earlier this year. What this means, essentially, is that some voters may be more likely to even answer polls when they think things are going well for their preferred candidate.

This means some Clinton supporters, because they got the sense that she won and feel excited, might be overrepresented in polls of the next few days. Conversely, some Trump supporters might not be in the mood to answer polls because they aren’t happy with how the debate went.

Still, the initial indicators we have look good for Clinton, who was itching for some good news for her campaign. So we’ll see if more methodologically rigorous polls that come in later this week find that there was a serious impact on where the race stands.