File:Voteline center squeeze.png

English: Illustration of the center squeeze effect in different voting systems.

The left-to-right axis represents any spectrum of opinion, such as a typical political spectrum, desire for a particular pizza topping, etc.

The voters are distributed along that spectrum according to the bell curve at the top.

The voters vote honestly in the 5 different voting systems shown, choosing the candidate(s) closest to them on the ideological spectrum. So someone a little to the right of the Green candidate, under different systems, would vote like this:

• Plurality: Green
• Approval: Green and Blue ("Voters are assumed to vote for all candidates within an acceptable distance.")
• Borda/Condorcet/IRV: Green > Blue > Red

The votes are then tallied according to the different systems and the winner is shown in the bars on the bottom, if the population were centered on that point.

In this diagram, the Blue candidate is a centrist candidate whose position most closely matches the average of all the voters. Systems with center squeeze effect (plurality and IRV) exclude the Blue candidate from winning, choosing either Red or Green depending on whether the population shifts slightly left or right. The other methods choose the Blue candidate, with Borda actually giving the Blue candidate an advantage.

The tool also allows for bimodal distribution and uniform distribution. The overall result is similar for each, though Borda helps the Blue candidate even more in the case of bimodal. "The Borda count is often described as a consensus-based voting system rather than a majoritarian one."

Generated from http://zesty.ca/voting/voteline/, which is GPL software http://zesty.ca/code/

Similar to: https://electology.org/center-squeeze-effect