ABC News
Six versus half-a-dozen

OK, I think I’ve finally figured out what Chuck Todd and the First Read guys are talking about:

As for the actual meeting itself, there’s one more angle you ought to be aware of: a 50% cut and a halving of the delegates is not the same thing. For instance, if Florida delegates are seated in their entirety, but only have their vote counted as a .5, then Clinton will net approximately 19 delegates out of the state. But if the delegation is cut in half, that’s done in every congressional district as well as statewide, then suddenly Clinton’s advantage is only a net of six. That’s right, the complicated nature of the DNC delegate selection process will be a good reminder to math majors everywhere that a 50% cut is not the same as a halving of an individual number. Go figure…

The distinction is in the way that the delegates are divided up in individual congressional districts. Take for example a district that Clinton won 70-30, and that originally had 4 delegates. If you do the multiplication, you get 2.8 fractional delegates for Clinton and 1.2 for Obama, which rounds up to a 3-1 delegate take for Clinton.

But now suppose that this district only has 2 delegates because Florida’s delegation has been cut in half. With her 70 percent of the vote, Clinton wins 1.4 fractional delegates, and Obama 0.6. However, Clinton’s number now rounds down to 1 delegate, whereas Obama’s rounds up to 1 delegate. So the same district that went 3-1 for Clinton with four delegates (+2) instead is split 1-1 if it has 2 delegates. On the other hand, if the district had four half-delegates, Clinton would win it 1.5-0.5, for a one-delegate advantage.

To be clear, there’s nothing intrinsic about halving the number of delegates that works to one or another candidate’s advantage. But I tried to re-create Todd’s math in Florida, and it indeed appears to be the case that the delegate thresholds just so happen to fall such that Clinton loses a few extra delegates due to what amounts to rounding error. This does not appear to be the case in Michigan; in fact, it looks like Clinton might make out a delegate or two better in that state if this method is applied.

Nate Silver founded and was the editor in chief of FiveThirtyEight.