Remember that poll from Forum that so many dismissed as "nonsense"? Well, it might still be the case that Forum was off, but the recent trend in the Nanos numbers are consistent with the Forum's numbers.
The 4-week average of Nanos now has the Liberals with a 6 points lead over the Conservatives (38.5% versus 32.5%). That's down from a +12 two weeks ago!
Some will say "LPC still ahead". That is technically true but Nanos is averaging over 4 weeks, so adjustments are painfully slow. Let's do some math to find the numbers of this week (or the last two only).
Let's compare to the numbers 5 weeks ago (so we are comparing two different samples). On August 22nd, Nanos had the following numbers:
LPC: 41,9
CPC: 30.9
NDP: 16.4
Green: 5
Bloc: 4.3 (18.2 in Qc)
The new numbers with data from the last 4 weeks:
LPC: 38.5
CPC: 32.5
NDP: 14.6
Green: 5.7
Bloc: 6.2 (25.3 in Qc)
The LPC's lead went from +11 to +6 in 4 weeks. On the other hand, dropping from 41.9 to 38.5 is not a statistically significant variation with 1000 observations. So keep that in mind.
Comparing the two full sample is nice but if Forum is right, the changes occurred in September only. Using the numbers from each week and doing some rough/approximate calculations, we get the following numbers for the last week only:
LPC: 29.9
CPC: 37.9
NDP: 11.3
How do I get that? As I said, approximate calculations. But if the Liberals were around 41% in the previous 3 weeks and are now at 38.5%, it means the Liberals were significantly below 38.5% this week (that's how an average work after all).
Of course, these numbers here are an approximation and are based on a very small sample size (250). Still, if there is really something happening, Forum and Nanos are all of a sudden not that far from each other.
The questions are naturally: is something really happening and why? For the former, we'll have to wait for confirmation by other polls and firms. I maintain my theory that the Forum's variations were a combinations of a house effect (Forum has the CPC higher), sampling variation and true, genuine variation. I think Nanos is about to corroborate this theory. As for the latter... I can only think of the proposed tax reform.
If this is what is really going on, then this tax reform would have done what a new Tory leader couldn't do after his election, or what the controversy about the Khadr payout didn't do: make the Liberals support drop.