UPDATE: New polls from Campaign Research and Forum Research were released on July 31, and they have been used to update the By-Election Barometer. In terms of the turnout model as discussed below, applying it to Forum's latest polls changes the look of them rather significantly.
A few weeks ago, I discussed how a simple turnout model was able to significantly increase the accuracy of polls in some recent elections. Depressingly so - the model requires ignoring the voting intentions of those under the age of 35. But nevertheless the model worked. Can it be applied to the Ontario by-elections that will be taking place on Thursday?
The first question to ask, however, is whether the turnout adjustment should be applied. Earlier this month, I took a detailed look at Forum Research's by-election track record and found it to be decent. If we take those same polls and apply the turnout model, we see that it turns these decent polls into very good ones. (You will need to click on the chart in order to magnify it.)
Now that it is quite clear that the turnout model can improve polls, let's apply it to the latest set of by-election polls Forum has recently released.
In fact, across the board it appears that turnout will work against the Liberals. The adjustment is nowhere worth more than two points, but with the PCs gaining between two and four points due to turnout it puts the OLP in a much more precarious position. Without the adjustment, the Liberals could expect to win Scarborough-Guildwood and have a shot at Etobicoke-Lakeshore and, maybe, Ottawa South. With the adjustment, the Liberals are out of the running in every riding but Scarborough-Guildwood. If these sorts of trends hold, the Progressive Conservatives could pick up three seats (maybe even four) and the NDP one. That would be quite a blow against the government.
Final by-election polls are to be expected this week. I will be interested to see how the NDP is doing in London West and whether the Liberals will remain competitive in Scarborough-Guildwood, Etobicoke-Lakeshore, and Ottawa South. But as it stands, Thursday is setting up to be a difficult day for Kathleen Wynne.