Wednesday, October 5, 2011

Ontario Election and polling

I look at the polling numbers and I am not certain which ones are giving the best data.   Between September 29th and October 4th there were 10 polls in the field.

  • Nanos - 4
  • EKOS - 3
  • Ipsos Reid - 1
  • Abacus Data - 1
  • Angus Reid - 1

Here are the ranges from the 10 polls

  • Liberals - 33% to 41% (8 percentage points)
  • PCs - 29.1% to 36.4% (7.3 percentage points)
  • NDP - 22.7% to 26.8% (4.1 percentage points)
  • Greens - 1.2% to 7% (5.8 percentage points)
The results should all be much closer together.   Total range should not be more than about 5 percentage points for the Liberals and should really be more like 3 percentage points if the methodologies in use are working well.   Different companies and different polling mechanisms should be fairly close together.

Could the variation of the polling numbers be due to the campaign?  In my opinion this is not the case.  The lowest and highest results for the PCs come from polls that were in the field on more or less the same days.   The Liberal results from the Angus Reid and Abacus Data polls were 4 percentage points apart and released on the same day.   If you assume the real support is half between the two the odds of the results from the two polls happening is less than 1 in 400.   The only answer is that some of the pollsters methodologies are flawed.  Though who would that be?

There are more sources of error going on than just the statistical measure of confidence.   

One could average of all the polls, but this means we build in a larger error as the accurate modelling is weakened by the inaccurate modelling.   

So, in my parsing of all the bits and pieces from the various polls and factoring for likely and unlikely voters and some more factors, I come to roughly the following support levels:
Liberals - 38.5%
PCs - 34.0%
NDP - 22.5%
Greens - 4.0%

My numbers are higher for the PCs and the Liberals than Eric at ThreeHundredEight.  I think the main reason there is a difference is because I am assuming the NDP will get less of the popular vote than the polls because more non-voters are saying they want to support the NDP.

My prediction at the moment of the Ontario election:
  • Liberals 52
  • PCs 38
  • NDP 17
Much will depend on the close races fall out and the Liberals could win a majority.

If it is a minority government, this would be sixth minority government.   Past ones were in:
  • 1919 when the United Farmers of Ontario came out of nowhere to win the most seats
  • 1943 which was the first win by the PCs in their 42 run of government.   The CCF came out of nowhere to win official opposition
  • 1975 first Davis minority government
  • 1977 second Davis minority government
  • 1985 Conservatives won the most seats but an agreement between the NDP and Liberals allowed David Peterson to become premier.

No comments: