[EM] Median bifurcation using pairwise matrix
royone at yahoo.com
Wed Aug 15 13:14:01 PDT 2001
I'm afraid I've scrambled two different methods under one name.
Median bifurcation, as I originally intended it, groups the
candidates based on median *rank*. As Forest pointed out, a majority
of voters can rank the CW in the lower half, which would rule him
out, so it fails Condorcet (but it takes a pretty polarized
electorate to do that).
The pairwise matrix version doesn't use median rank, it uses wins vs.
losses, which may be some kind of median, but it's not an equivalent
method. I recommend calling it Win-Loss bifurcation; it is (as Rob
LeGrand pointed out) very similar to Nanson's. In fact, it's probably
equivalent: the only difference is that mine uses Row_total -
Column_total and compares to zero (which is average), whereas Nanson
compares row totals to the average of the row totals. It's the first
example I've seen of bifurcation in election methods. But then, I'm
not particularly well-read yet.
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