Blair boosted by more supporters saying they will vote

A new poll for the Guardian tomorrow by ICM has Labour six points ahead. The headline figures are with changes on the last ICM poll: LAB 39 (+1) : CON 33(nc) : LD 21 (-1)

The main drive behind the new figures is a greater desire of Labour supporters to actually vote. Those who said they would definitely go to the polling stations shot up from 52% to 59%, while the proportion of Conservatives who said they would certainly vote shifted upwards by only a fraction from 64% to 65% on the last Guardian ICM poll last week.

This will give a lot of comfort to the Labour team. The Lib Dems will be a touch disappointed to see their rating go down and the fact that the Tories are stuck on 33% will be frustrating for Michael Howard.

With all these phone surveys we are mighty reliant on the complex mathematics that the pollsters use to produce headline figures from the raw data.

ICM weight by past voting recall and add about a tenth to Labour because it’s argued that people are more likely to say they voted for Tony Blair last time when they might have forgotten. The pollster also has a “spiral of silence calculation” that gave Labour 2% extra in one of it recent polls. We’ll know on May 6th whether they’ve got this right.

ICM FORM NOTE: The last time the pollster was tested against real results was in 2001 when they overstated the Labour lead by just under 2% – an excellent performance. Unfortunately it was slightly udermined by another larger survey that was started at the same time that had an overstatement of nearly 8%. They did not carry out surveys for the Scottish elections in 2003 or the June 2004 Euro elections.

The main betting message from this is that turnout could be substantially higher than the 59% of four years ago. We still think that the 6/5 that you can get for a turnout of 63+% is great value as is the 60.25-61.5% spread from IGIndex.

SITE NOTICE. We are moving house tomorrow so there will be few site updates.

Mike Smithson