In this final, though not very conclusive, post on political analysis, we’re talking voting, voting systems, and ice cream.
The Median voter theorem helps explain the importance of the swing voter. For the MVT there are four elements:
- A set of n voters where n is odd (apparently an even number can work too, but we didn’t really talk about it, and, as in Minecraft, odd numbers just work better.)
- Unidimensional policy space (i.e. right vs. left, socialist vs. capitalist, more funding vs. less funding)
- Voters have quadratic or “single-peaked” preferences that can be represented by the equation U[x] = [x1 – x’]2. So they have one ideal point (x’) and whichever option falls closer to their ideal point is what they’ll vote for.
- The group makes decisions by majority rule (and we’ll talk about alternatives to this in a bit.)
The theorem states that, if every voter in the group has an ideal point, the voter with the median ideal point is an indicator of how the group will vote.
To apply this, here’s an example:
The International Space Committee is voting between two bills to send colonists to Mars. There are seven seats on the committee. Three of them are hardliners who think colonization is a waster of resources, and their ideal point is 0 colonists. On the other end of the spectrum is a sci-fi fan who wants to send a hundred colonists. Then in the middle we have someone who wants to send three colonists, someone who wants to send five, and someone who wants to send twelve. Read More »