Showing posts with label voting rule theory. Show all posts
Showing posts with label voting rule theory. Show all posts

Wednesday, May 19, 2010

Philippine Elections: In A Hypothetical Runoff Elections, Will Noynoy Aquino Still Be The Winner?

Perhaps not.

That's if we base this on Kenneth Arrow's Impossibility Theorem.

Just a reminder, in the Philippines we have a plurality and not a majority representative government, therefore, runoff elections are precluded.

Runoff elections by definition is a "two-round system (also known as the second ballot, runoff voting or ballotage) is a voting system used to elect a single winner."

In other words, if we were to pursue a majority representation, then the top two contenders, Aquino and Estrada would have to compete again in a second round of elections to secure the top spot through a majority vote.

Perhaps we can talk about more of this once the final outcome have been declared.

Anyway, what may be popular may not be the actual. Professor Don Boudreaux lucidly explains how under the "Impossibility Theorem" the outcome of the popular elections may dramatically change, under a runoff.

And when applied to Philippine national elections the outcome may be a surprise.

Here is Professor Boudreaux,


Suppose there are nine voters.

Voters 1, 2, 3, and 4 each prefer candidate A to candidate C and candidate C to candidate B. That is, each of these four voters ranks the three candidates as such: A>C>B.

Voters 5, 6, and 7 rank the candidates like this: B>C>A.

Voters 8 and 9 rank the candidates like this: C>B>A.

In the general elecation, A will receive 44.4 percent of the vote (4 of 9 votes cast); B will receive 33.3 percent of the vote (3 of 9 votes cast); and C will receive 22.2 of the vote (2 of the 9 votes cast).

[my comment- this looks somewhat like the distribution share of the still pending final count for Presidential election results- where Aquino has 40.19%, Estrada has 25.46% and Villar has 14.22% (wikipedia.org). To consider the above theory is based on 3 contenders while we have 9 contenders for the recent election!]

Because no candidate won a majority of the vote in the general election, a runoff election is held between the top two vote-getters from the general election: candidates A and B.

In the runoff election, candidate B will win 55.6 percent of the vote (5 of 9 votes cast). B will then be sworn into office, presumably as the voters’ preferred candidate.

But look more closely. Suppose that the candidate who received the fewest votes in the general election – candidate C – were to run against candidate B in a runoff election. Which of these two candidates would win? Answer: C. In such an election, C would win 66.7 percent of the vote (6 of 9 votes cast), thus trouncing candidate B! (Also note that if a runoff election were to pit C against A (the candidate who received the most votes in the general election), C would also defeat A: C would get 55.6 percent of the vote (5 of 9 votes cast) to A’s 44.4 percent (4 of 9 votes cast).

So is it correct to say that candidate B is the voters’ most-preferred candidate? Clearly not.


Nevertheless, Professor Don Boudreaux concludes, ``The point of this exercise is to make clear that describing the winner of any fair and honest election as being the ‘choice of the voters’ is fraught with potential inaccuracies."

Indeed.