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by ClayShentrup 1829 days ago
> Approval voting I think is much too tactical and, strictly speaking, worse than IRV.

On the contrary, approval voting gets better results than IRV with any measure of strategic or honest voters. See extensive computer simulation results by Harvard stats PhD and voting methods expert Jameson Quinn. Brown (50/50) is probably the most realistic setting.

https://rpubs.com/Jameson-Quinn/VSE5key

A simple example of IRV strategy is next year's Alaska senate race. Murkowski would beat either rival head-to-head but is likely to be eliminated based on first-place votes. So Democrats want to strategically rank Murkowski 1st in order to help her survive to beat Tshibaka (Trump Republican) so they at least get their lesser evil.

Here's a good comparison of approval voting vs. IRV by experts. Full disclosure, I was a CES co-founder and have written extensively on this topic for 15 years.

https://electionscience.org/library/approval-voting-versus-i...

> I honestly thought that after learning Arrow’s impossibility theorem that Condorcet is not especially important.

I've visited Kenneth Arrow at his home and co-founded a non-profit that interviewed him. His theorem only applies to social welfare functions, not voting methods, if properly understood. But if anything, the moral is to AVOID ranked voting methods and instead use rated voting methods.

https://www.rangevoting.org/ArrowThm

2 comments

For those who want to better understand VSE simulations and those who want to compare even more voting methods, see: http://electionscience.github.io/vse-sim/VSE/
Or if you want to see an animated version narrated by the gp of this comment (Clay) see this: https://www.youtube.com/watch?v=-4FXLQoLDBA
> On the contrary, approval voting gets better results than IRV with any measure of strategic or honest voters. See extensive computer simulation results by Harvard stats PhD and voting methods expert Jameson Quinn. Brown (50/50) is probably the most realistic setting.

If you look at the graph with the honest strategy you get better results with IRV which is basically his point.

We shouldn't assume 100% honest strategy in reality. It is an idealistic metric. It's not practical since people aren't 100% informed. Nor should we only consider optimal strategy. We need to consider the max, min, and median to determine robustness and better estimate real world results. Both the max and min for Approval is better than the max and min of IRV (in other words, the range is smaller and the expected result is more representative).