If anyone tells you that "tactical voting" is possible on Thursday, they're either misleading you or they don't know what they're talking about

Over the last few weeks I've made the point a number of times that it's not possible to "vote tactically" in the European elections, regardless of whether the intended effect is to increase the chances of Scottish independence or to increase the chances of Britain remaining in the European Union.  We all just have one vote for one party, and seats in the European Parliament will be allocated in proportion to the share of the vote received by each party.  It's hard to think of a voting system less conducive to tactical voting than that.  And yet in recent days there have been two determined attempts to convince the public that pro-Remain tactical voting is both feasible and desirable.  First of all Gina Miller gave a suspiciously hazy summary of research based on "machine learning" that claimed, among other things, that Remain supporters in Scotland should tactically switch to the SNP on Thursday.  Then a website called 'Remain Voter' gave an even sketchier explanation for their advice that Scottish voters should switch tactically to the Liberal Democrats.

As there is a direct contradiction between the two recommendations (Miller and 'Remain Voter' also contradict each other in Wales and some of the English regions), it hopefully won't be too controversial if I say that both can be safely ignored.  But what's going on here?  I suspect Miller's initiative is well-intentioned but misguided - she's probably seen the dramatic effect of tactical voting in first-past-the-post elections (it cost the Tories a lot of seats in 1997, for example) and imagines that the same can be achieved in any election, regardless of the voting system.  She's used opinion polling to estimate the state of current voting intentions and then commissioned experts to judge which tactical movements between one Remain party and another would maximise the total number of seats won by Remain parties.  But that's where she hits the age-old problem: the results you get out are only as good as the data you put in.  She's betting the house on her poll results being exceptionally accurate, and if they're not, her recommendations will have no sound basis.  Yes, she's using the most advanced polling methods, but the extreme level of accuracy required for the exercise is simply beyond what is actually possible.  I would guess her experts must understand that perfectly well, but if you're being paid handsomely it's easy enough to turn a blind eye to that sort of fundamental snag.

I'm rather less charitable about the motivations of the 'Remain Voter' website, because their stated logic for the Lib Dem recommendation in Scotland is so mind-bogglingly perverse that it's hard to believe there isn't some sort of agenda behind the whole thing.  Here it is in all its glory -

"Scotland is interesting! Recent polling shows SNP confidently gaining 3 seats with undecided Labour voters blocking a 4th.

Remain Voter modelling shows LDs have the momentum to win a seat while helping the SNP win the 4th seat.

Smart voting can win a seat from a pro-Brexit party while capitalising on Labour's lack of commitment to their majority Remain membership."

Yes, folks, they really are saying that "tactically voting for the Lib Dems" can somehow "help the SNP to win a fourth seat".  Which is arithmetically impossible.  The lack of explanation for how they think the laws of mathematics can be bent on this occasion is rather deafening.  Someone suggested to me on Twitter that if a very large number of Labour voters were to switch to the Lib Dems, that could achieve the claimed effect, with the Lib Dems taking one seat and the SNP taking four.  But that's not "tactical voting" - that's voters switching sides from a Leave party to a Remain party.  The whole thing is absolute gibberish.

The only limited sense in which there's a grain of truth in the claims about tactical voting is that if you vote for a pro-Remain party that has no realistic chance of winning a seat in your electoral region (that would apply to Change UK in Scotland and in most other electoral regions), you're wasting your vote and you'd be better off voting for a more popular Remain party (ie. the SNP, Plaid Cymru, the Greens or the Liberal Democrats).  But beyond that very narrow point, the system really can't be gamed, and you should just vote for whichever party you like best and agree with most.