Although the methodology for the new breed of Google voting intention surveys is dubious, comparisons between one survey and the next may at least be of some assistance in keeping track of the trend as the election campaign progresses. Today's survey shows a swing back to the SNP - not big enough to be statistically significant, but there's certainly no sign of a Tory surge. The snag, though, is that I can't find the fieldwork dates - if we don't know whether the survey preceded or followed the local elections, it's difficult to make much sense of the numbers.
Google survey of Scottish voting intentions for Westminster (Don't Knows NOT excluded) :
SNP 40.7% (+1.8)
Conservatives 24.4% (-0.2)
Labour 16.8% (-1.0)
Greens 7.0% (-1.4)
Liberal Democrats 5.3% (-0.9)
One of the oddities of these surveys is that, unlike almost all voting intention polls, the headline figures don't exclude Don't Knows. However, it's easy enough to do a rough calculation to strip out the Don't Knows, which takes us to...
Liberal Democrats 5.6%
A 17% SNP lead is the biggest of the campaign so far - and remember, the Greens' 7.4% share is pretty meaningless given that they aren't standing in the vast majority of constituencies. It can't be automatically assumed that most of their vote is really destined for the SNP, but a decent chunk of it certainly is, and hardly any of it is destined for the Tories. So, if this survey can be taken seriously, the SNP's lead is somewhat bigger than 17%.
More details and analysis to follow...