ExampleSingle Transferable Vote - STV

Suppose an ice-cream "election" is conducted to determine which flavour to serve at a birthday party.

• There are 5 flavours "candidates", 3 of which will be chosen.

• The candidates are: Vanilla, Neopolitan, Chocolate, Strawberry, and Licorice.

• The 20 guests at the party have the preferences marked on their ballots in the two tables below
(the first is a numerical representation, the second is pictorial).

In this election only the first 2 preferences of the voter is shown, because in this case their lower preferences will not affect the result.

# of Guests -->
x x x x x x x x x x
x x x x
x x x x x x
1st Preference




2nd Preference


to clarify above - 4 guests (x x x x) prefer vanilla 1st, neopolitan 2nd; 2 guests prefer neopolitan 1st, vanilla 2nd; 8 guests want chocolate 1st, strawberry 2nd; etceteras

Next- the quota is calculated.
Using the Droop quota*, with 20 voters and 3 flavors (candidates) to be chosen, the number of votes required to be "elected" is:

\left({20 \over {3+1}}\right) +1 = 6
                             * see and understand Droop quota as this is the difficult Math concept

When ballots are counted the election proceeds as follows:

Candidate:
Round 1 x x x x x x x x x x
x x x x

x x x x
x x Round 1: Chocolate is declared elected, since Chocolate has more votes than the quota - 6 
Round 2 x x x x x x x x x x
x x
x x x x
x
x x x Round 2: Chocolate's surplus votes transfer proportionately to Strawberry and Licorice according to the Chocolate voters' second choice preferences. However, even with the transfer of this surplus no candidate has reached the quota. Therefore Neopolitan, who has the fewest votes, is eliminated.
Round 3 x x x x
x x
  x x x x
x x
x x x x
x
x x x Round 3: Neopolitan's votes transfer to their second preference, Vanilla, causing Vanilla to reach the quota and be elected. Vanilla barely meets the quota, and therefore has no surplus to transfer.
Round 4 x x x x
x x
  x x x x
x x
x x x x
x
x x x Round 4: Neither of the remaining candidates meets the quota, so Licorice is eliminated. Strawberry is the only remaining candidate and so wins the final seat.

Result: The winners are Chocolate, Vanilla and Strawberry.