ComRes rolling-poll - 35/25/27
The figures for ComRes's rolling poll tonight are CON 35%(nc), LAB 25%(-1), LDEM 27%(+1), with changes from yesterday. The poll is made up of samples from Monday and Tuesday.
In the comments below the last post there was quite a lot of discussion about the maths of the rolling poll, and whether the consistency of this poll supports yesterday's big jump in the Tory lead that ComRes found, but none of the other pollsters did.
As far as I'm aware ComRes's rolling poll is interviewing 500 people a day, and each days figures are made up of the last two samples. What appears to have happened this week is that ComRes had figures pretty much in line with other companies in their Monday poll - suggesting pretty normal samples on Saturday and Sunday. Their Tuesday poll dropped the Saturday sample and added the Monday sample, which pushed the Tories up 3 and knocked Labour and the Lib Dems down 2, suggesting a Monday sample with a very large Tory lead. Today's figures keep that very Conservative Monday sample, but replace the Sunday data with data from Tuesday.
The fact the figures haven't changed implies that Tuesday's data is much the same as Sunday's, and that ComRes's bigger Tory lead is all down to a strange sample on Monday. ComRes only do their rolling poll between Monday and Wednesday, so we won't get any figures tomorrow. If we did, then the Monday sample would be dropped and replaced with data from Wednesday, and would probably have shown the Tory lead shrinking again.