Do you believe the pollster’s mathematics?
FACT: For their Mirror survey published this morning 341 people told ICM that they had voted Labour last time. Yet only 291 said that they were planning to vote for the party on May 5th â€“ a decline of about a sixth
YET the headline figure that was published was that Labour would get 41% – just one percent down on what the party got four years ago.
SO the opinion poll that has been driving the betting markets is based on ICM methodology that turns 17% into 1%.
With the Tories it worked the other way. Nearly a fifth more people told the pollster that they were voting for Michael Howardâ€™s party than said they voted Conservative last time. Yet the headline figure from ICM had them with an increase of just over 1%.
With the Liberal Democrats the difference was even more marked. The number who told the pollster that they were supporting Charles Kennedyâ€™s party was over a quarter than the number who said they voted this way last time. Yet ICM only put the headline figure up 1%.
All this is based on ICMâ€™s view that people do not tell the truth when asked how they voted four years ago. To deal with this they have a complex equation which weights towards Labour and away from the Lib Dems and the Tories.
Are ICM right or are ICM wrong? Weâ€™ll know on May 6th.
In the meantime there might be good value in the betting markets. In 2001, in common with all other pollsters, ICM overstated Labour.