Ipsos poll shows National & Labour could get a combined 100% if they simply changed leaders!

This morning, Vernon Small reports that “Labour would get an immediate lift in the polls if it dumped leader David Cunliffe”. This is based on an Fairfax Ipsos poll which shows that if Cunliffe were to be replaced, Labour would lose 1.7% from existing Labour voters, but would gain 15.2% from other parties and undecideds – a net gain of 13.6%.

On the National Party side of the ledger, National would lose 5.3% of existing National voters, but would pick up 12.4% from other parties and undecided – a net gain of 7.1%.

There’s one slight problem though. Let’s do the maths…

The latest Ipsos poll, released yesterday, has National on 54.8%. Add on it’s 7.1% windfall if John Key were to be suddenly replaced, and National rises to 61.9%. Labour meanwhile jumps from 24.9% to 38.4%, should Cunliffe suddenly depart. That’s a total of 100.3% of the vote between the two parties. Which doesn’t make a lot of sense…

Nice one, Vernon…

UPDATE: Rob Salmond at Polity has a nice post on this issue, dealing with the dangers of inferring that “I’m more likely to support X” equates to “I am switching to X”.