A boost for Ming or the product of the firm’s methodology?

The latest poll from Mori in today’s Financial Times has with changes on the last poll at the end of June CON 36 (nc): LAB 32 (-1): LD 24 (+3). – so a big boost for the Lib Dem leader with the biggest share for the party since last September.

The poll is quite old. The survey started on July 20th – one day before work began on the July ICM survey for the Guardian – and finished on July 24th, a week ago.

Whatever figures that Mori are showing I never get too excited and would certainly never risk money on one of their polls.

Unlike ICM, Populus, and YouGov the Mori approach does not involves weighting its samples by past vote or a party identifier. It is thus much more reliant on getting a representative sample. The one filter it does use is that its headline figures only include those who say they would be “certain to vote” in a General Election.

Another factor that might have an impact is that the Mori “certainty to vote” question is put at the end of the interview while ICM has this at the start. It is often argued that later responses in a polling survey might be “conditioned” by what has been asked before.

Mori’s monthly party shares tend to be much less stable than the other pollsters and thus more newsworthy. Journalists love big changes and polls which one show minute movements get much less attention.

Thus the Sun made a big splash of the Mori poll last January that reported a 6% drop in the Lib Dem share to fifteen points. During that period the highly stable ICM polls never showed a Lib Dem share below 19%.

Whatever these numbers will certainly have a political impact because of the febrile situation created by the Middle East crisis. The Lib Dems seem to be on the right side of public opinion and this will reinforce Ming’s position.

Although the voting intention numbers are subject to the “certain to vote” filter this does not apply to the rest of the data from the survey. Among the others questions Mori has support for Blair at its lowest point ever and more people being against Cameron than for him.

To Lib Dems I would say – remember what you were saying about the Mori methodology after that 6% drop in January.

Mike Smithson