How good a predictor is this?
The chart shows how the Betfair prices on the by election have moved in the past twelve hours with the odds reflected as an implied probability.
If there is any information coming from on the ground then it’s hard to detect it having an impact. Certainly there’s nothing happened so far that has caused SNP backers to feel confident about backing their choice to tighter prices.
The general experience of by elections is that we do not see pronounced moves until after about 6pm when the party HQs start getting a real feel for whether they are in with a chance or not.