# [EM] STV anomaly - Part of my vote went to someone who was not on my list

Markus Schulze markus.schulze at alumni.tu-berlin.de
Sun May 1 06:41:43 PDT 2005

```Dear Jim Ronback,

the main aim of STV is to achieve Droop proportionality.
Suppose S is the number of seats and V is the number of
voters. Then "Droop proportionality" says:

If W > 0 voters strictly prefer every candidate
of a given set of N1 candidates to every other
candidate, then at least min {ceil((S+1)*W/V)-1; N1}
candidates of this set must be elected.

*******************************************************

In your example, V = 10000 voters and S = 4 seats.

W = 5100 voters strictly prefer each of the N1 = 4
candidates {A,B,C,D} to every other candidate.
min {ceil((4+1)*5100/10000)-1; 4} = 2.
Therefore, Droop proportionality says that at least
2 candidates of {A,B,C,D} have to be elected.

W = 4900 voters strictly prefer each of the N1 = 4
candidates {E,F,G,H} to every other candidate.
min {ceil((4+1)*4900/10000)-1; 4} = 2.
Therefore, Droop proportionality says that at least
2 candidates of {E,F,G,H} have to be elected.

The fact that the Meek method chooses {A,B,F,G} is in
agreement with Droop proportionality.

Markus Schulze

```