The latest YouGov poll, released on Sunday, has the Tory lead at a mere 2%. While Labour supporters should not get too excited, this is consistent with the trend over the past month to six weeks. Since YouGov essentially became a tracker poll on February 17, the Tory lead has been +9, +7, +8, +6, +6, +6, +6, +6, and now +2. If those +6 results reflect the true value of support at C 39, L 33, then this true value rests comfortably within the margin of error of the most recent poll. Hence, this Times column on the volatility of polling is sound advice, aside from his contention that “all polls have a margin of error of 2 points or so plus or minus”; +/- 3% is the norm due to the inefficiencies of diminishing marginal returns. This poll has an N slightly over 1400, which would place the margin of error slightly below 3%; in order to hit 2% the N would have to be around 2500.
I expect the next YouGov poll to move towards the earlier 6% lead, but the trend is clear: Labour are closing the gap for a variety of reasons (save for Gordon Brown, who still trails Cameron in head-to-head approvals). So what does either scenario mean?
If it’s Tories +6, at 39 to 33, the Tories would have 293 seats, Labour 280, the Lib Dems 46.
If at +2, at 37 to 35, then it’s Labour 316, Tories 256, Lib Dems 48.
Both scenarios assume a uniform national swing, which while not a completely safe assumption, is necessary in order to calculate the distribution of seats. The Tories ‘ground game’ strategy is to (intelligently) target the marginal constituencies at the expense of running a purely national campaign, and this may yield dividends that would warp the results expected from a uniform swing. However, even here, the Tories would come up well short if the gap is only 2%. In an analysis by Peter Kellner, president of YouGov, the Tories might realize 270 seats to Labour’s 300.
What is clear in any of these calculations, be it Tories +2 or +6, due to the vagaries of the British electoral system, neither party would hit the magic 326 necessary for an outright majority. This would result in a minority government and a new election within a year.