Additional Member System facts for kids
The Additional Member System is a special way of voting used in some places, like parts of the United Kingdom. It's designed to make sure that the number of seats a political party gets in a legislature (like a parliament) is more fair and matches the total votes they receive. This system tries to be more proportional than other voting methods, like First Past The Post, where only the candidate with the most votes wins, even if they don't have a majority.
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How You Vote and How Votes Are Counted
How Voting Works
When you vote in an Additional Member System election, you actually get two votes!
- Your first vote is for a specific person, called a local representative, who wants to represent your local area (your constituency). This is often called a constituency vote.
- Your second vote is for a political party. This is often called a list vote. This vote helps decide how many extra seats each party gets to make the overall result more fair across a wider region.
How Votes Are Counted
First, the votes for the local representatives are counted. The person who gets the most votes in each local area wins that seat. It doesn't matter if they got more than half the votes, just that they got more than anyone else.
After that, the "list seats" are given out. These seats are used to make the total number of seats each party has more closely match the percentage of votes they received in the party list vote. This helps smaller parties or parties that didn't win many local seats still get some representation.
An Example of How it Works
Let's imagine a simple election with 100,000 voters, 3 political parties, and 10 total seats (6 local seats and 4 extra "list" seats).
Here's how the votes and seats might look:
| Party | Local Seats | Party List | Total Seats | Total Seat Share | ||||
|---|---|---|---|---|---|---|---|---|
| Votes | Vote Share | Seats Won | Votes | Vote Share | List Seats | |||
| Party X | 43,000 | 43% | 4 | 45,000 | 45% | 1 | 5 | 50% |
| Party Y | 36,000 | 36% | 2 | 36,000 | 36% | 1 | 3 | 30% |
| Party Z | 21,000 | 21% | 0 | 19,000 | 19% | 2 | 2 | 20% |
How List Seats are Calculated
The list seats are given out using a special formula to make sure the final number of seats for each party is as fair as possible. Parties that won fewer local seats but got a lot of party list votes might get more of these extra seats.
Here's how the 4 list seats would be given out in our example:
| Party | Votes | Member Score | /1 | /2 | /3 | /4 | Seats Allocated |
|---|---|---|---|---|---|---|---|
| Party X | 45,000 | 9,000 | 9,000 | 4,500 | 3,000 | 2,250 | 1 |
| Party Y | 36,000 | 1,200 | 12,000 | 6,000 | 4,000 | 3,000 | 1 |
| Party Z | 19,000 | 19,000 | 19,000 | 9,500 | 6,333 | 4,750 | 2 |
In this example, Party Z didn't win any local seats, but because they got a good number of party list votes, they received 2 of the extra list seats, making the overall result more fair.
Where It's Used Now
The Additional Member System is currently used in several important elections:
- The London Assembly, which helps govern London.
- The Scottish Parliament, which makes laws for Scotland.
- The Welsh Assembly, which makes laws for Wales.
Italy's Electoral System
Italy has also used systems similar to the Additional Member System for its Parliament.
Mattarellum
From 1993 to 2005, Italy used a system sometimes called the Additional Member System, but officially known as Mattarellum. In this system, about 75% of the seats were decided by who got the most votes locally, and the remaining 25% were used to make the overall legislature more proportional.
Rosatellum
More recently, Italy adopted a new electoral law in 2017 called Rosatellum. This is also an Additional Member System. With Rosatellum, about 36% of the seats are decided by local votes, and a larger portion, 64%, are used to create a proportional parliament. This new law was supported by many political parties in Italy and was approved by their parliament in October 2017.
See Also
