Swingometer

The swingometer is a graphics device that shows the effects of the swing from one party to another on British election results programmes. It is used to estimate the number of seats that will be won by different parties, given an overall x% national swing in the vote towards or away from a given party, and assuming that that percentage change in the vote will apply in each constituency. The device was invented by Peter Milne, and later refined by David Butler and Robert McKenzie.