Predict next national post-debate Democratic poll

[Mr. Morden]

No Biden
- Clinton gains a lot
- Bernie picks up a little
- O'Malley gains (but more than if Biden were included)

How can Clinton, Sanders, and O'Malley all gain at the same time?  There aren't that many percentage points to work with among Chafee/Webb/Undecided.

[Mr. Morden]

I think you need to distinguish between “probability to win the nomination” and “current standing in the polls”.

On standing in the polls, Clinton may gain some in the polls that include Biden.  But in the polls that don’t include Biden, she already has such an enormous lead (she’s leading Sanders by at least 20, and sometimes 30, in every national poll that excludes Biden, while O’Malley, Chafee, and Webb are at a combined ~2%) that I don’t see how she’s going to go any higher.  She went into this with a big lead in simple name recognition, even over Sanders.  Just by appearing on the same stage with her, Sanders and O’Malley could end up gaining a little support at her expense.

But that doesn’t matter.  How big her polling lead over Sanders is doesn’t matter.  The bottom line is that she performed well enough to dissuade any supporters from jumping ship on her, at least in the short term.  And the short term is what really matters, since there are zero debates left between now and the first filing deadlines to get on primary ballots.  So her probability of winning the nomination has definitely increased.