An Analysis of Tactical Voting Sites for UK General Election 2019

I’ve been following the debate about tactical voting in the 2019 UK General Election, and particularly the controversy about Best for Britain’s site getvoting.org, which is accused of giving “bogus” advice based on a fairly opaque methodology (see this Guardian article).

So… I decided to get the constituency-by-constituency data from this site and a couple of others (tactical.vote and tacticalvote.co.uk) to see how they compare, and whether they pass a basic “plausibility” test based on % voting swing needed from 2017 results.

I narrowed down my analysis to the 317 seats won by the Conservatives at the 2017 General Election, since these are the core focus for tactical voting, whether to Stop Brexit or just get the Tories out. This chart shows which party came second in each of these constituencies in 2017.

I narrowed down again to look at % swing needed for the Liberal Democrats or Labour to win in each constituency. The baseline tactical strategy would be to vote for whichever party came closest to beating the Conservatives in 2017, and this is almost exactly what tactical.vote advises.

The same plot for getvoting.org shows something very different. Even on the assumption of a huge swing from Labour to the Lib Dems on 12 December, there’s no plausible “tactical” case for voting for Lib Dems in clear Tory/Labour marginals like Watford or Hendon.

Meanwhile, tacticalvote.co.uk takes a more sensible/cautious approach by reserving judgement on many constituencies until later in the election campaign. As the 2017 General Election and 2019 EU Election showed, there can be a huge shift in public opinion during this short period.

Almost by definition, “tactical voting” is worthless if voters who want the same thing follow contradictory advice. Whatever the “science” behind getvoting.org, its advice contradicts the others and doesn’t pass a basic plausibility test, so I would suggest to view it with extreme caution.

You can see all the data that I compiled for this analysis in this Google Spreadsheet. The constituency-by-constituency data is based on this spreadsheet compiled by Britain Elects.