More 2011 Election Metrics – Department of Cautionary Tales
May 9th, 2011
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[Welcome, National Newswatch readers!]
Continuing our series of post-election metrics, I wonder: could we please lay the following faulty rules of thumb to rest, once and for all.
1. If a riding was close last time, it's a riding to watch this time.
No. In fact this is now the Pundits' Guide Prime Directive™:
"Just because a riding was close last time, doesn't necessarily mean it will be close this time."
Of the 42 ridings that were close in the last general election (i.e., within 5%), only 12 were still close this time. And 39 of the ridings that WERE close this time – that's the vast majority of them – were NOT close last time.
|2008 General Election|
|Marg <= 5%||Was Close||Not Close||ALL|
|2011 GE||Was Close||12||39||51|
Or, if you prefer the criterion to be within 10%, only 30 of the 79 races that were within 10% last time were still within 10% this time. And 51 of the close races in 2011 – again the vast majority of 81 closest contests – were NOT close contests last time.
|2008 General Election|
|Marg <= 10%||Was Close||Not Close||ALL|
|2011 GE||Was Close||30||51||81|
By the way, four ridings have been within 5% in each of the last four elections:
- Ahuntsic, QC – (and who knows how this riding will look next time around, if the Bloc Québécois no longer exists as a federally registered party)
- Burnaby-Douglas, BC
- Esquimalt-Juan de Fuca, BC – (and if I had to guess, won't be close next time, since the Liberal anomaly here won't be a factor next time around)
- Vancouver Island North, BC
2. We can know which seats are most likely to change hands this time (and will be "ridings to watch"), because they will have been amongst the closest seats last time.
In incremental elections, just under half the seats that will change hands were previously won by 5% or less, and around three-quarters will have been previously won by 10% or less.
But in transformational elections, those percentages drop substantially. In 2004 and 2011, just under one in five of the seats that would change hands had previously been won by 5% or less, and only around one in three had been previously won by less than 10%.
Thus, in order to know whether the previous margin is predictive of a seat's likeliness to change hands, it seems you need to know ahead of time whether the election will be incremental or transformational. In other words, good luck with that.
This methodology could miss at least a quarter – and as many as two-thirds – of all the ridings that will change hands in an election.
[UPDATE: I described the difference between incremental and transformation elections in a blogpost, found here, before the current election.]
Seats Changing Hands Party-Wise, by Previous Margin (either By-election or General Election), 2004-2011
|0 – 5%||28||25||19||18|
|5 – 10%||16||18||10||19|
|10 – 15%||10||3||6||13|
|15 – 20%||19||4||3||13|
|20 – 25%||15||2||1||13|
|25 – 30%||9||3||1||7|
|30 – 35%||6||0||0||8|
|35 – 40%||5||0||0||4|
|40 – 45%||8||0||0||2|
|45 – 50%||7||0||0||0|
|50 – 55%||5||0||0||1|
|55 – 60%||5||0||0||0|
|60 – 65%||1||0||0||0|
3. If a riding were going to change hands, the second-place finisher last time will usually be the party that wins it.
Only in incremental elections. Not the case in 1993, 2004, 2011.
Note that the government didn't change hands until 2006, but 2004 saw the most upheaval (the result of the merger between the two conservative parties).
Seats by Previous Rank of Winning Party (either By-election or General Election), 1993-2011
|Previous Rank of Winning Party||Total
|* Winning party did not exist, or winner had been/became Independent, etc.|
You'll notice that I picked these three assumptions, because they were the ones used by the various amateur seat projector/predictors and the strategic voting sites which depended on them. We'll be taking a look at those next.