Those of us who have been watching the polling daily know that there is a wide difference in the forecast of a Clinton win among several outfits….
Vox has a oiece on why the Nate Silver projection over at Five Thirty Eight tends to be favorable to a Clinton win, but less so….
According to FiveThirtyEight’s estimate, Clinton currently has about a 3.4 percent popular vote lead. But her chances of winning are only 70 percent or higher in contests where 272 electoral votes are at stake. If she wins them all, that’s just barely enough to get her over the top.
So how likely is it that there will be either a polling error (either nationwide or in enough states to tip the scale) or a last-minute swing the polls simply don’t have time to pick up on (again, either nationwide or in enough key states)?
All the other models are essentially telling us that given the data we have, these scenarios are very unlikely to transpire — but Silver’s is warning not to count it out. After all, back in 2012, polling averages ended up underestimating Barack Obama’s national margin of victory by 2 to 3 points. So how safe is a Clinton national lead of 2 to 3 points, really?
This is in part due again to Silver’s aggressive weighting of his state forecasts to changing national and regional numbers, even when we haven’t had many new polls in particular states in a while.
To oversimplify, the other models are leaning more towards assuming that with so much polling in so many states showing Clinton narrowly ahead, it’s highly unlikely that they’ll all be wrong in the same way. But Silver’s model thinks a “miss” in national polling would likely be reflected in swing states too — even states that have been considered part of Clinton’s “firewall” up until now.
There’s sound basis in the historical data for painting the states with a broad brush, since on average, national movement does appear to show up in the swing states too. But then again, the swing states are in a different world than the rest of the country in some ways — they’re subject to millions of dollars more in ads, as well as extensive voter turnout operations. So they might not just follow along with the national trend, particularly in a year when the two campaigns are so different.
More broadly, though, Silver’s forecast is just more uncertain that the result will match what the current polling data shows (while still assuming that’s the most likely outcome). As Silver has written, his model also assumes a higher likelihood of a Clinton landslide win than many of the others. And this treatment of uncertainty better accounts for the fact that, well, we genuinely don’t know what will happen in the future….
I have called Silver out on twitter for covering his back on his call…
The above Vox piece above says nothing different….Share on Facebook