Tuesday, April 28, 2015

Swing batta swing

Needless to say, the range of potential outcomes in the Alberta election (along with the continued flow of news battering the Prentice PCs as they try to regain some type of footing) has made for a fascinating campaign. But it's worth pointing out that single polls and seat projections may miss important parts of the picture - meaning that the actual state of the race is far less certain than it might appear at first glance.

Take for example this important explanation of Election Almanac's methodology:
Election Almanac uses a proportional swing model for its projections based on the latest election poll results. For example, if a poll gives a party a greater (multiplied by a factor greater than 1) share of the vote than they received in the last election, the projector assumes the party’s vote has gone up by the same proportion in every seat. Conversely, if a poll gives a party a smaller (multiplied by a factor less than 1) share of the vote than they received in the last election, the projector assumes the party’s vote has gone down by the same proportion in every seat. No projection model is 100% accurate. 
Now, a presumption that all seats will see identical swings between parties might make for a useful initial assumption. But the last Alberta election was based on a radically different set of party strategies and goals.

In 2012, the Redford PCs veered left in order to paint themselves as a relatively moderate alternative to a perceived Wildrose government-in-waiting - so most of the province's seats were decided by the allocation of a two-way split among 78% of Alberta voters. Meanwhile, the NDP's primary focus was on holding onto beachheads rather than expanding its support throughout the province.

Today, we can say with some certainty that the situation has changed. Rather than fighting primarily in the few most friendly Edmonton ridings, the NDP is looking to sweep the city, while the PCs are turning to the right and chasing a larger share of right-wing voters to try to stop the orange wave. And the rest of the campaign will determine which seats actually are the swing ridings - with surprises likely to pop up along the way.

For all the news in the headline poll numbers, though, there's relatively little means for the public to figure out exactly how those will translate into seats. And that goes doubly in a three-way race where (for example) ThreeHundredEight's seat projection sees the PCs' seat count potentially ranging from 5 to 31 based on a swing of under four points in popular support.

In theory, it might be possible to try to use more sophisticated means to generate seat projections - for example, by also comparing regional and seat-based polling to the 2011 results to test the assumption of a uniform swing. But increased complexity is no guarantee of greater accuracy, especially when subtle shifts (particular in the last-minute choices of undecided voters) can swamp the effect of any further adjustment.

Meanwhile, it's also worth keeping on eye on the parties' plans, since they'll likely have the best information as to which seats are close. But the parties themselves face a range of goals which may include maximizing votes, maximizing seat totals, and maximizing the possibility of a plurality or majority government. And I'm particularly curious as to whether the PCAA will bet heavily on a high-variance strategy, preferring to exhaust every hope of maintaining hegemony over Alberta politics rather than making any substantial effort to rebuild from the opposition benches.

To summarize, we should be hesitant to draw overly precise conclusions from the poll results generated so far: while it seems safe to say the order in party support is currently NDP 1, Wildrose 2 and PC 3, the noise far outweighs the signal when it comes to projecting the seats which will ultimately determine who forms government. And so no party should be resting on its laurels as the campaign draws to a close.

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