STV Basics: quick revision, 12 bites

What is STV?

One vote, many choices, fair results.

**Single Transferable Vote (STV)** is a **proportional representation** system where voters rank candidates by preference. Instead of just picking one, you order candidates from favorite to least favorite. If your top choice is eliminated or already has enough votes, your vote **transfers** to your next preference. Thi…

Takeaway. STV makes every vote count by letting it move to your next choice.

How STV Counting Works

Follow the vote transfers step by step.

Takeaway. STV repeats transfer and elimination until every seat is decided.

The Quota Formula

How many votes do you need to win?

Takeaway. The quota ensures no more winners than seats.

STV in Action: 2 Seats

A small example makes it clear.

Imagine 100 voters electing 2 seats. Quota = floor(100/3)+1 = 34. Candidates A, B, C, D run.

Takeaway. Surplus and eliminated votes flow to other candidates.

STV vs. First-Past-the-Post

How STV differs from simple plurality.

Takeaway. STV aims for proportional representation, unlike FPTP.

Where is STV Used?

Real places, real elections.

Takeaway. STV is used in several countries for fair representation.

Ranking Too Few Candidates

Don't stop at your favorite.

Takeaway. Rank more to keep your vote alive.

Surplus Transfers

Extra votes don't go to waste.

When a candidate exceeds the quota, the **surplus** (votes above quota) is transferred to the next preferences on those ballots. This ensures that as many votes as possible help elect someone.

Takeaway. Surplus votes are redistributed, not discarded.

Remember the Quota

Quota is the key number.

In exams, always calculate the quota first. Then track transfers carefully. Practice with small numbers to avoid mistakes.

Takeaway. Quota calculation is the first step in any STV problem.

Invented in the 19th Century

A system with a long history.

STV was invented independently by **Thomas Hare** in England and **Carl Andræ** in Denmark in the 1850s. It has been used for over 150 years.

Takeaway. STV is a time-tested electoral method.

STV as a Dinner Party

Think of choosing a menu.

Imagine a group ordering pizzas. Everyone ranks toppings. If the most popular choice is already ordered, your vote goes to your next favorite topping. This way, the final order reflects everyone's preferences as much as possible.

Takeaway. STV is like ranking your pizza toppings to get a fair mix.

For Voters: Rank Sincerely

Honest ranking is the best strategy.

In STV, you don't need to worry about 'wasting' your vote. Rank candidates in your true order of preference. There's no advantage to strategic voting.

Takeaway. Vote your true preferences in STV.