According
to Duverger's law, the electoral rules of a district determine the
number of effective parties. SMDP rules should produce two effective
parties, and proportional representation rules should produce more.
To test this theory let's look at the electoral rules and the number
of effective parties in Turkey.
First
we need to look at the electoral rules of Turkey. Turkey uses
proportional representation rules for elections (Wikipedia). From
this knowledge we should expect Turkey to have multiple effective
parties (if Duverger's law is correct). Let's further our study of
the electoral rules of Turkey first to better understand the
relationship between the type of rules and the number of effective
parties. The Grand National Assembly of Turkey has 550 directly
elected seats and 79 electoral districts (Parline 2012). This gives
Turkey an electoral magnitude of about 7. Turkey allocates these
seats according to the d'Hondt formula (Parline 2012). Turkey does
not have a hybrid system, so all the votes are distributed according
to the d'Hondt formula. Turkey also has a preferential list
structure that allows voters to decide on the party list (Wikipedia).
Finally, Turkey has a 10% threshold (Parline 2012). This threshold
means that each party has to have at least 10% of the nationwide
votes to be counted.
Next
let's look at the number of effective parties in Turkey. To
calculate the number of effective parties we will take the inverse of
the sum of the percentage of party votes squared. Using data from
the June 2011 election in Turkey, the sum of the percentage of party
votes squared is as follows: (0.49)2+(0.26)2+(0.13)2+(0.07)2+(0.01)2=
0.33 (Wikipedia). Now we take the inverse, which tells us the number
of effective parties in Turkey is 3.
The
case of Turkey lends support to Duverger's law. Turkey uses
proportional representation electoral rules and has 3 effective
parties. Just as Duverger's law says, the use of proportional
representation rules allows a country to have a greater quantity of
effective parties.
REFERENCES
Parline.
2012. Inter-Parliamentary Union.
http://www.ipu.org/parline-e/reports/2323_B.htm (accessed November
1, 2012).
Wikipedia.
Turkish general election, 2011.
http://en.wikipedia.org/wiki/Turkish_general_
election,_2011(accessed November 1, 2012).
It is interesting that even with a threshold as high as 10%, Turkey still adheres to Duverger's Law.
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