Blog 7: Duverger's Law

Mark Mackey

Pl Sc 150

Blog 7: Duverger’s Law

            Different countries around the world have very different party systems. The United States of America, for instance, has only two major parties that consistently win elections. Other countries have a much larger number of competitive political parties, such as Serbia. The relationship between party systems and electoral systems is theorized in Duverger’s law. This law claims that single-member-district plurality (SMDP) electoral systems “encourage the emergence of two large parties,” while proportional representation (PR) systems encourage “a variety of smaller parties” (Shively, 233). The case of Serbia’s National Assembly seems to validate Duverger’s law.

Effective Parties

The National Assembly is the unicameral legislative branch of Serbia, and the most recent election held for the body was on May 6, 2012 (“Serbia”). In this election a total of eleven parties won seats in the parliament, with the largest numbers awarded to the Let’s Get Serbia Moving party, the Choice for a Better Life party, and the Ivica Dacic coalition. However, not every party that won a seat can be counted as effective. The equation N_eff = 1/Σp² can be used to find the number of effective parties in any party system. Using this equation and the data in the table below, the number of effective parties in Serbia is 4.9.   

Party	Seats	Proportion
Let’s Get Serbia Moving	73	.292	.085
Choice for a Better Life	67	.268	.072
Ivica Dacic	44	.176	.031
Democratic Party of Serbia	21	.084	.007
Turnover	19	.076	.006
United Regions of Serbia	16	.064	.004
Five other parties	10	.04	-
Total	250	1.0	.205

(data from Wikipedia, “Elections in Serbia”) 

This number is clearly illustrated in the election results. Three parties received the majority of the votes, as stated above, yet several other parties were awarded a relatively large amount of representation in the Assembly (accounting for the additional 1.9 effective parties). Since Serbia’s electoral system is a PR system (“Serbia”), these results strongly support Duverger’s law.

Electoral Rules

           

As mentioned above, the National Assembly of Serbia is a unicameral parliamentary body. There are 250 directly elected representatives in the Assembly, and elections are held every four years. A single nationwide constituency elects all 250 members, making the district magnitude 250/1, or 250. Seats are allocated proportionally using the d’Hondt method. Serbia’s electoral system consists purely of proportional representation – there is no hybrid use of SMDP (SMDP would not work anyway in Serbia’s electoral system since there is only one district – the entire country). The list structure the country uses in voting is somewhat open: candidates can be submitted by political organizations and coalitions as well as by citizen groups, which have to be supported by at least 10,000 voters. Parties must pass the threshold of five percent of the total vote in order to win a seat in the assembly, but parties “representing coalitions of ethnic minorities” do not have to reach any threshold to win seats (“Serbia”). Five such coalitions won seats in the National Assembly in the 2012 election (“Elections”).

Sources

“Elections in Serbia.” Wikipedia. http://en.wikipedia.org/wiki/Elections_in_Serbia (accessed November 1, 2012).

“Serbia: Narodna skupstina (National Assembly).” Inter-Parliamentary Union. http://ipu.org/parline-e/reports/2355_B.htm (accessed November 1, 2012).

Shively, W. Phillips. Power & Choice: An Introduction to Political Science. New York City: McGraw-Hill, 2012. (accessed November 1, 2012).