Pre “adjustment” ICM has LAB and CON level-pegging – after it the Tories are 6% ahead
Before ICM's adjustment for don't knows+refusers LAB had small lead. The headline figures were CON lead of 6% pic.twitter.com/RnhkpXqkvn
— Mike Smithson (@MSmithsonPB) November 17, 2015
After “adjustment” Con 39 (+1) Lab 33 (-1) UKIP 12 (+1) LD 7 (nc)
In a note of explanation the pollster observes:
It should be noted, however, that the raw data shows substantive change which our newly strengthened adjustment process disguises. Based on (pre-adjusted) turnout weighted data, the parties are neck and neck, which the manual adjustment converts into a 6-point Conservative lead.
This is due to unusual combination of three factors. Firstly, the sample recalls voting in a Labour government for the fourth time out of six occasions since the last election (which is frustrating, but not the unusual part) but secondly, the level of partial refusal (respondents who told us what they did in 2015 but don’t know/refuse to tell us what they would do next time) this month has cut into the Conservative share significantly. In previous polls subsequent to the General Election, partial refusers have been fairly evenly balanced between the two parties.
Thirdly, the Conservatives are rounded up from 38.5% to 39%, and Labour rounded down from 34.4% to 34%.
In short, the adjustment has offset potential sampling imbalance and has worked to correct data outcomes in exactly the way we intended them to in light of the General Election polling miss.”
We’ll get the first details of inquiry into the GE2015 polling failure on January 19th.