Alternative explanations

Chrystal rightly points out that the drop in Canadian voter turnout in 2008 looks to have been largely centred in the 45-74 age range, signalling unusual disengagement by a set of voters which would normally be relatively active. But while I agree with her view that a more proportional system would be a plus generally, I'm not sure we can blame the same electoral system that a voter would have been familiar with for upwards of half of his or her life for a sudden dropoff in that age range.

Instead, I'd think there are two more obvious explanations as to how it's that group in particular that decided not to vote.

First off, there's the issue of partisan attachments in the context of a woefully weak Liberal campaign. For younger voters turned off by Stephane Dion's frailties and the lack of party support behind him, the lack of a long-term voting pattern would seem to make it comparatively easier to look to an alternative. But those who had been voting Liberal for decades may have been more likely to stay home rather than supporting the NDP or the Greens - and all indications are that Libs supporters did so in droves.

But that isn't a full explanation either since turnout was down for all parties but the Greens. And that leaves the possible effect of the new voter identification rules imposed by the Cons, Libs and Bloc.

My first impression would have been that the voters most affected would likely be found in the oldest and youngest cohorts where they'd be less likely to have all of the required ID. But that doesn't seem to have been a problem for voters 75+, who actually made up the lone group which increased its turnout from 2006. So could it be that the greatest effect of the new ID requirements was to restrict the turnout among older working Canadians who may have figured that it wasn't worth the trouble to go to the polls?

(Edit: fixed typo.)