VP Debate: Polls Find Mixed Results

As my co-panelist S.E. Cupp at theBlaze predicted yesterday, CNN's vice presidential debate flash telephone poll concludes the debate was a draw. But a CBS News online poll of undecided voters found Biden the winner.

According to the CNN poll of 381 debate watchers, 48 percent of voters who watched the vice presidential debate thought Rep. Paul Ryan won, 44 percent thought Vice President Joe Biden won.  Ryan came across as more likeable by a margin of 53 percent to Biden's 43 percent. Debate watchers also thought Ryan communicated more clearly, by a margin of 50 percent to 41 percent. Half of debate watchers said the debate did not impact their vote, 28 percent said they are now more likely to vote for Republican presidential candidate Mitt Romney, 21 percent are more likely to vote for President Barack Obama. From this poll alone, it's hard to say whether the debate merely reinforced viewers' existing voting intentions, or actually impacted their votes. The CNN poll found equal numbers of Republican and Democratic debate watchers, unlike conventional polls which find more self-identified Democrats than Republicans. This difference in partisan composition may explain Ryan's edge in the poll.

Perhaps more predictive of the debate's actual impact is a CBS News poll of 431 undecided voters who watched the debate. Among them, 50 percent thought Biden won, 31 percent thought Ryan won. Eighty-five percent of these undecided debate-watchers thought Biden had a strong command of the issues, compared to 75 percent who thought so of Ryan. Before the debate 45 percent of undecided voters thought Ryan would be an effective president, 39 percent felt similarly about Biden. However, after the debate 56 percent thought Biden would be an effective president, while only 49 percent thought the same of Ryan. 

The two polls differ in sample selection, which impact the external validity of their results. The CNN poll interviewed respondents who on a previous national telephone poll said they planned to watch the vice presidential debate and agreed to a follow up interview. The CBS Poll interviewed respondents CBS previously asked to watch the debate, from a probability-based online panel. So arguably, not all the CBS poll watchers would have watched the debate without the prompting. Consequently, the CBS poll demonstrates what a representative sample of undecided voters would think of the debate had they chosen to watch, but not necessarily of the debate's actual impact among those who chose to watch the debate.