So even though your vote won't change who wins the election, you will still shift the policies of the parties towards your own views.
You don't achieve this by voting -- you achieve this by loudly proclaiming that you will vote on the basis of issues A, B, and C.
I think half an hour to go and vote is probably more effective than half an hour of loudly proclaiming, but I can't think of a test for this. Perhaps look at elections where the vote showed that what people wanted was different from what the media said people wanted, and then see which way the parties moved.
Previous Open Thread: http://lesswrong.com/r/discussion/lw/k9x/open_thread_may_26_june_1_2014/
(oops, we missed a day!)
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
Notes for future OT posters:
1. Please add the 'open_thread' tag.
2. Check if there is an active Open Thread before posting a new one.
3. Open Threads should start on Monday, and end on Sunday.
4. Open Threads should be posted in Discussion, and not Main.