15 October 2015

A natural cycle in Canadian federal elections?

We’ve started looking into what might be a natural cycle between governing parties, which may account for some of our differences to the polls that we’ve seen. The terminology often heard is “time for a change” – and this sentiment, while very difficult to include in voter characteristics, is possible to model as a high level risk to governing parties.

To start, we reran our predictions with an incumbent-year interaction, to see if the incumbency bonus changed over time. Turns out it does – incumbency effect declines over time. But it is difficult to determine, from only a few years of data, whether we’re simply seeing a reversion to the mean. So we need more data – and likely at a higher level.

Let’s start with the proportion of votes received by each of today's three major parties (or their predecessors – whose names we’ll simply substitute with modern party names), with trend lines, in every federal election since Confederation:

This chart shows that the Liberal & Conservative trend lines are essentially the same, and that the two parties effectively cycle as the governing party over this line.

Prior to a noticeable 3rd party (i.e., the NDP starting in the 1962 election and its predecessor Co-operative Commonwealth Federation starting in the 1935 election) the Liberals and Conservatives effectively flipped back and forth in terms of governing (6 times over 68 years), averaging around 48% of the vote each. Since then, the flip has continued (10 more times over the following 80 years), and the median proportion of votes for Liberals, Conservatives, and NDP has been 41%/35%/16% respectively.

Further, since 1962, the Liberals have been very slowly losing support (about 0.25 points per election), while the other two parties have been very slowly gaining it (about 0.05 points per election), though there has been considerable variation across each election, making this slightly harder to use in predictions. (We’ll look into including this in our risk modeling).

Next, we looked at some stats about governing:
  • In the 148.4 years since Sir John A. Macdonald was first sworn in, there have been 27 PM-ships (though only 22 PMs), for an average length of 5.5 years (though 4.3 years for Conservatives and 6.9 years for Liberals).
  • Parties often string a couple PMs together - so the PM-ship has only switched parties 16 times with an average length of 8.7 years (or 7.2 Cons vs. 10.4 Libs).
  • Only two PMs have won four consecutive elections (Macdonald and Laurier), with four more having won three (Mackensie King, Diefenbaker, Trudeau, and Crétien) prior to Harper.

All of these stats would suggest that Harper is due for a loss: he has been the sole PM for his party for 9.7 years, which is over twice his party's average length for a PM-ship. He's also second all-time behind Macdonald in a consecutive Conservative PM role (having past Mulroney and Borden last year). From a risk-model perspective, Harper is likely about to become hit hard by the “time for a change” narrative.

But how much will this actually affect Conservative results? And how much will their opponents benefit? These are critical questions to our predictions.

In any election where the governing party lost (averaging once every 9 years; though 7 years for Conservatives, and 11 years for Liberals), that party saw a median drop of 6.1 points from the preceding election (average of 8.1 points). Since 1962 (first election with the NDP), that loss has been 5.5 points. But do any of those votes go to the NDP? Turns out, not really: those 5.5 points appear to (at least on average) switch back to the new governing party.

Given the risk to the current governing party, we would forecast a 5.5%-6.1% shift from the Conservatives to the Liberals, on top of all our other estimates (which would not overlap with any of this analysis), assuming that Toronto would feel the same about change as the rest of the country has historically.

That would mean our comparisons to recent Toronto-specific polls would look like this:

Remember – our analysis has avoided the use of polls, so these results (assuming the polls are right) are quite impressive.

Next up (and last before the election on Monday) will be our riding-level predictions.

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