It tells you how often you have to be thinking about "playing the
strategy game" to improve the outcome (or how often you may regret if
you don't). In a low manipulability method, you don't have to start
thinking about whether you should tailor your response to poll data,
etc. as much.
Chances of being able to vote honestly, with no strategic burden to bear.
That's what the manipulability numbers are about.
@Filip Ejlak tersander@gmail.com @Kristofer Munsterhjelm
km_elmet@t-online.de I think this paper may interest you
https://www.journals.uchicago.edu/doi/pdf/10.1086/726943, because they
measure something closer to what both of you were talking about: what are
the chances that I, a typical voter, will have no strategic burden to bear?
The results have the opposite conclusion from the manipulability
experiments by KM. The chances you'll have to "play the strategy game"
are higher in IRV than in FPP!
As a statistician, my strongest piece of advice for interpreting
probabilities: "never calculate a probability without rigorously defining
your sample space first". If you care about the probability that a
person will
have to vote strategically, you can't substitute that for the probability
that an election involves strategy. Corporations elections are not people!
If what you care about is the amount of strategic burden on a voter, you
need to calculate *that *number, not a different number.
Which is a big part of why approval/score/etc. are some of my favorite
methods, by the way. None of this messing around with 12-d chess to work
out the best ranking. I just place my approval cutoff between the
frontrunners, who I can find by Googling "538 polling average". Then I go
about my day as usual, knowing I've done my part to guarantee majority-rule
will prevail (because this strategy ends with the Condorcet winner being
elected).