Here at PEC, the likely range of electoral votes is set by assuming that opinion can drift in either direction, by an equal amount across states; and then converting that swing into electoral votes. This generates the red “strike zone” in the plots in the right sidebar. Today I make a small update.

When the previous relationship was established in June, few states were weak for Trump; indeed, in many states we were reliant on 2012 election results, in which Mitt Romney ran stronger than Trump is now. That meant that opinion swings toward Clinton would not change the electoral-vote (EV) estimate much. That led to an asymmetric strike zone. In fact, there was a whole region around 342 EV where multi-percentage-point polling swings led to no change at all. Full disclosure, it was not an ideal calibration curve.

Now that we have fresh polling data, it is possible to recalculate the relationship between margin and seats in the prior. Trump leads are fairly evenly distributed, including some states where he barely leads. The same is true for Clinton. Therefore a swing of opinion in either direction now leads to corresponding changes in EV.

Note that this change does not affect the November win probabilities at all. That probability treats a bare EV win and a blowout the same way. The exact number of electoral votes does not matter.

P.S. Yes, this aspect of the calculation – the conversion of Meta-Margin for purposes of November EV estimation – was not automated! It will be soon – one of several outstanding issues. I realize that it would have been more satisfying to see the change unfold gradually.