Exactly one month ago, the UK woke up to the news they had elected a hung parliament for the second time in three elections.  For many forecasters including myself, this came as a surprise as I had been predicting a Conservative majority of 100 seats.  In the event, the largest ever polling underestimate of the Labour vote was enough to see the Conservatives lose their majority.

At the beginning of my commentary on election night itself, I defined success for my forecasts as being how close the number of Conservative seats was to my forecast of 375.  I also stated that if the number of seats was in the 340s I would consider this to be a prediction error.  The final outcome was 317 seats so clearly that is a major prediction error.

**Update 20th Sept 2025 – This post was originally published 9th July 2017.  It remains one of my most important posts but it did contain some graphics which were unreadable in some formats and some typos so I’ve edited this post to correct these issues.  I’ve also updated the text format to my current style guide and taken the opportunity to add links to subsequent posts which reinforce particular points made in this article.  Any new links are pointed out**

[Read more…] about UK General Election 2017 #7 – Review of my predictions