Voting intention polls in the UK are accurate after all!

For years, I’ve observed that UK polls on average underestimate the Conservative vote and overestimate Labour’s vote.  When I converted poll data into forecasts of seats won, I had to first estimate how much polling error there would be.  So what’s changed?  It turns out I was comparing polls to the wrong statistic, namely national vote share.  The correct comparator is in fact average vote share per seat.

[Read more…] about UK General Elections #7 – How accurate are voting intention polls? – Revised