On turnout

Alice has some excellent advice for anybody who wants to focus unduly on cutting into other parties' support as the main growth strategy for the NDP:

Using the per cent of the electorate rather than per cent of the vote allows us to look at the fastest-growing “party” of the last 20 years in British Columbia: non-voters. In fact, if the non-voters were a political party, they would have won every B.C. seat in 2008 except Saanich-Gulf Islands and Surrey-White Rock-Cloverdale.

Looking at elections results this way, we notice that Conservative support has remained fairly constant in most B.C. federal ridings since 1988. It’s just that the turnout is down.
...
NDP support is most likely to drop when turnout drops, since their support correlates with low-income status, and that correlates with lower voter participation. And in 1993 as the NDP vote plummeted in virtually every B.C. riding, about half of the drop could be accounted for by big increases in non-voters. But in 2004, the B.C. seats showing the biggest gains for the NDP were also seats where turnout went up.

So, Byers may want to go back to the drawing board to find a more successful formula, and perhaps a different dance partner.

Of course, the alternatives aren't necessarily mutually exclusive: presumably some of the same messages which may help to win additional voters away from other parties may also get some new participants involved in the political process, and the NDP will likely need a mix of both to continue its recent growth. But to the extent there's a choice to be made, there's more theoretical upside to be found in working to boost turnout overall than in following suit with the Harper Cons' brand of slice-and-dice politics - and it may be that the next possible wave of support for the NDP among regular voters will only surface once it's brought out enough new participants to reshape the current party standings.

Incidentally, it's worth noting that the by-elections themselves provided a strong example of the dangers of low turnout in a riding where the NDP made relatively modest gains compared to what it may have hoped for:

An official with Elections Canada said that based on by-election data they had available dating back to 1960, Monday’s 22.3 per cent turnout in Hochelaga is the lowest.

I've pointed out one side of the equation in the riding, to the effect that a clear cross-party push would be needed to make the NDP the default federalist option for the riding. But with the Bloc taking more than half the riding's votes as it was, it's apparent that no amount of federalist cooperation will flip ridings like Hochelaga unless it's paired with some additional turnout as well.

All of which is to say that for all the differences between Canada's assorted regions, the most important part of the NDP's formula for growth may well be the same across the country. And while it will be difficult to tell before a general election whether the party has made any progress in reversing the recent slide in voter interest, that may be the ultimate measure as to whether the NDP can continue to build from its current position.