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Comparing Proportional Representation Electoral Systems: Quotas, Thresholds, Paradoxes and Majorities

  • Michael Gallagher


The relationship between electoral systems can be examined on a number of dimensions. Seat allocation methods are conveniently divided into two groups: those based on largest remainders and those based on highest averages. The single transferable vote has its own distinct characteristics. Focusing on certain elements – the quota, thresholds, paradoxes and the conditions under which a majority of seats can be won – enables comparisons to be drawn between seat allocation methods. Certain seat allocation methods conventionally seen as variants of proportional representation (PR) cannot be regarded as such. PR methods can be rank ordered according to whether, when complete proportionality is not attainable, they display electoral bias towards larger or smaller parties. However, a definitive ordering is elusive, since some methods that are generally more favourable to larger parties can in some circumstances set lower thresholds of representation than methods generally favourable to smaller parties.



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1 Amoroso, Mario, ‘Italy’, in Hand, Geoffrey, Georgel, Jacques and Sasse, Christoph, eds, European Electoral Systems Handbook (London: Butterworths, 1979), pp. 140–69, at p. 158.

2 The terms ‘smaller’ and ‘larger’ are entirely relative. For a more formal demonstration that larger parties benefit from a low quota, see Appendix.

3 For example, Rae, Douglas, The Political Consequences of Electoral Laws, revised edn (New Haven and London: Yale University Press, 1971), p. 34, says that, compared with LR-Hare, LR-Imperiali lowers the price of the first seat, thereby ‘helping weak parties’.

4 For an English translation of his article, see Lijphart, Arend and Gibberd, Robert W., ‘Thresholds and Payoffs in List Systems of Proportional Representation’, European Journal of Political Research, 5 (1977), 219–44, pp. 241–2.

5 Carstairs, Andrew McLaren, A Short History of the Electoral Systems in Western Europe (London: George Allen and Unwin, 1980), pp. 26–9, 42.

6 Balinski, Michel L. and Young, H. Peyton, Fair Representation: Meeting the Ideal of One Man, One Vote (New Haven and London: Yale University Press, 1982), pp. 26–8.

7 For equal proportions, see Huntington, Edward V., ‘A New Method of Apportionment of Representatives’, Quarterly Publication of the American Statistical Association, 17 (1921), 859–70. For the circumstances in which the Danish method is used, see Johansen, Lars Norby, ‘Denmark’, in Hand, , Georgel, and Sasse, , European Electoral Systems Handbook, pp. 2957, p. 46. Pure Sainte-Laguë was used at the first four post-war Danish elections – I owe this information to Arend Lijphart. The only reference of which I am aware to the employment of Imperiali highest averages is to be found in Van Den Bergh, G., Unity in Diversity: A Systematic Critical Analysis of all Electoral Systems (London: B. T. Batsford, 1956), pp. 25, 96, where it is stated that the method is used for municipal elections in Belgium.

8 Carstairs, , Short History of Electoral Systems, p. 29.

9 Balinski, and Young, , Fair Representation, p. 104.

10 So do LR-Hare and LR-Droop, but LR-Imperiali does not function effectively as its low quota of 3,704 votes would ‘allocate’ twenty-six seats initially. It too, therefore, cannot be classified as a PR method. We are excluding STV from this part of the discussion as it embodies a more sophisticated conception of ‘perfect proportionality’ by considering voters' lower preferences.

11 Gallagher, Michael, ‘Proportionality, Disproportionality and Electoral Systems’, Electoral Studies, 10 (1991), 3351.

12 Van Den Bergh, , Unity in Diversity, p. 96.

13 Lijphart, Arend, ‘Degrees of Proportionality of Proportional Representation Formulas’, in Grofman, Bernard and Lijphart, Arend, eds, Electoral Laws and Their Political Consequences (New York: Agathon, 1986), pp. 170–9, at pp. 172–5; Balinski, and Young, , Fair Representation.

14 Carstairs, , Short History of Electoral Systems, p. 19.

15 The method is illustrated by Van Den Bergh, , Unity in Diversity, pp. 6872.

16 For a full account of how STV operates in Ireland, see Hand, Geoffrey, ‘Ireland’, in Hand, , Georgel, and Sasse, , European Electoral Systems Handbook, pp. 121–39.

17 Lakeman, Enid, How Democracies Vote, 4th edn (London: Faber and Faber, 1974), p. 147.

18 Newland, Robert A., Comparative Electoral Systems (London: The Arthur McDougall Fund, 1982), p. 64. A similar point is made by Hill, I. D., ‘Some Aspects of Elections: To Fill One Seat or Many’, Journal of the Royal Statistical Society A, 151 (1988), 243–75, at pp. 253–4, 273; and by Rokkan, Stein, ‘Electoral Systems’, in Sills, David L., ed., International Encyclopedia of the Social Sciences, Vol. 5 (New York: Crowell Collier and Macmillan, 1968), pp. 621, at p. 15.

19 Quoted in Humphreys, John H., Proportional Representation: A Study in Methods of Election (London: Methuen, 1911), p. 138. See also Lakeman, , How Democracies Vote, p. 148; Newland, , Comparative Electoral Systems, p. 64.

20 Vote management at this election may have affected the outcome in eleven of the forty-one constituencies. It is discussed in Gallagher, Michael, ‘The Election Results and the New Dáil’, in Gallagher, Michael and Sinnott, Richard, eds, How Ireland Voted 1989 (Galway: Centre for the Study of Irish Elections, 1990), pp. 6893, at pp. 81–3.

21 This philosophy is outlined in Huntington, ‘A New Method of Apportionment’.

22 Lijphart, , ‘Degrees of Proportionality’, p. 176.

23 Lijphart, and Gibberd, , ‘Thresholds and Payoffs’. See also Rokkan, , ‘Electoral Systems’, pp. 1315; Rae, , Political Consequences of Electoral Laws, pp. 149–70; Rae, Douglas W., Hanby, Victor and Loosemore, John, ‘Thresholds of Representation and Thresholds of Exclusion’, Comparative Political Studies, 3 (1971), 479–88; Laakso, Markku, ‘The Maximum Distortion and the Problem of the First Divisor of Different PR Systems’, Scandinavian Political Studies, 2 (1979), 161–9; Taagepera, Rein and Shugart, Matthew S., Seats and Votes: The Effects and Determinants of Electoral Systems (New Haven and London: Yale University Press, 1989), especially pp. 274–7.

24 Mackie, and Rose, , International Almanac, p. 510.

25 Lijphart, and Gibberd, , ‘Thresholds and Payoffs’, p. 229.

26 Both are demonstrated by Lijphart, and Gibberd, , ‘Thresholds and Payoffs’, pp. 228–9.

27 Balinski, and Young, , Fair Representation, p. 39. Another example of the Alabama paradox is given by Carstairs, , Short History of Electoral Systems, p. 25. In the case he illustrates, a hundred seats would be awarded on a 45–44–11 basis under both LR-Hare and Sainte-Laguë, while if the number of seats is increased to 101, Sainte-Laguë produces a 45–45–11 outcome whereas under LR-Hare the smallest party loses a seat and the outcome is 46–45–10.

28 Newland, , Comparative Electoral Systems, pp. 40–2.

29 Balinski, and Young, , Fair Representation, p. 69.

30 Brams, Steven J., Paradoxes in Politics (New York: Free Press, 1976), p. 157.

31 Balinski, Michel L. and Young, H. Peyton, ‘The Quota Method of Apportionment’, American Mathematical Monthly, 84 (1975), 450–5; Balinski, and Young, , Fair Representation, pp. 7981 and 129–34.

32 This is demonstrated by Balinski, and Young, , Fair Representation, p. 90.

33 For example, Van Den Bergh, , Unity in Diversity, p. 25. The other side of the argument is that a large party can often win a majority of seats with a minority of votes under d'Hondt, LR-Droop and STV if the other votes are scattered among a number of opponents. This may happen under Sainte-Laguë and LR-Hare, though it would require a greater degree of fragmentation of the other votes, and cannot happen under Adams.

34 Gallagher, , ‘Proportionality, Disproportionality and Electoral Systems’.

* Department of Political Science, Trinity College, University of Dublin. I am grateful to Arend Lijphart, Ivor Crewe and the anonymous referees for comments on an earlier draft. The usual disclaimer applies.


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