Handling Overhang Seats [this page in German] [ Overhang Seats Mean Page ]

There are three (or four) ways to proceed with overhang seats:
  1. Take the number of overhang seats off from the other parties' seats (compensatory)
    (e.g. National Council Elections in Austria, Scottish Parliament Election, planned system in Great Britain)
    Characteristics: Reinforcement of unproportionality, unchanged total number of parliament seats.
  2. Allow the overhang
    (e.g. Federal State Parliament (Landtag) of North-Rhine/Westphalia until 1965)
    Increases total number of seats. Reduces Proportionality.
  3. Additional balance seats
    (most election of the federal parliament systems, e.g. current North-Rhine/Westphalia)
    Strengthened increase of the total mandate number. No (reduced) Disproportionality.
  4. Non-awarding of overhang seats
    In this case, no overhang seat, develop by definition. The non-awarding was applied occasionally in Bavaria.

These procedures are used all in different combinations. Thus, there can be a distribution of additional balance seats whose number is limited, however (e.g. on the number of overhang seats).

The first method is most favorable for an over-hanging party , the latter is the least favorable.

However, whether the electoral system remains meaningful must be considered due to the various possible combinations of handling. E.g. Saxonia-Anhalt, where additional balance mandates are distributed (method 3), although the over-hanging party receives less than 5 per cent of the party votes, in this case seats are taken off the other parties (method 1).
This leads to the effect that, in 1998, the SPD would have had a substantially better result, if the party had gotten less than 5% of the party votes.

Effects of different Dealings with Overhang Seats

Overhang Seats

Examples of these Effects

Parties Votes Seats
with PR
Taken from 
Taken | Remain 
| Compensation Compensator-
Nationalists 39.497 4 2 |   | |
Labour 37.605 4 1 | -1 | |
Liberal 31.655 3 5 |   | |
Conservatives 26.989 2   |   | |
Green 13.935 1   |   | |
Socialists 9.000 1   | -1 | |
SUM 158.681 15 | 15  -2 | 17  | 23 
          |     |   |    
Votes per Seat   9000     |
9402   |
9000 |

In this example the Liberal Party gains 5 constituencies and consequently, 2 overhang seats. There are 15 seats to distribute in general (Normal Seats). The Proportional Representation should be calculatetd by the Divisor method with rounding down (D'Hondt/Hamilton).
  1. Take the number of overhang seats off from the other parties' seats :
    Taking the overhang seats from the other parties will in this case reduce the number of seats of the Socialists and Labour each by one. The total number of seats remains 15. The Proportionality is reduced. Each Party needs 9402 votes per seat, only for the liberals the ratio votes per seats is 6330.
  2. Leave the overhang without compensation:
    The Liberals stay with their overhang seats, the other Parties retain their seats by PR. The PR is a little bit higher. The total number of seats is increased by two overhang seats from 15 to 17. There are 9000 votes for a seat, only the ratio for the liberals is 6330.
  3. Additional Balance seats:
    To compensate the overhang Seats, additional balance seats are distributed, thus one seat is rewarded for 6330 votes. The nationalists and the conservatives receive two seats, Labour and the Green Party receive one balance seat. The total number of seats increases from 15 to 23.
  4. Not Awarding
    Two of the five constituency seats are not awarded to the liberals. The total number of seats remains at 15. For 9000 votes a party wins a seat.

Note: everything applies to external overhang seats only. Other possibilities apply to internal overhang seats. The introduction of additional balance seats for internal overhang seats leads to additional problems (Example Baden-Wuerttemberg)
© 2002 Martin Fehndrich