The Convergence Coefficient across Political Systems

Table 2

The convergence coefficient in plurality systems.

	United States			United Kingdom
	2000	2004	2008	2005	2010
Weight of policy differences (𝛽)
Est. 𝛽; (conf. Int.^a)	0.82; (0.71, 0.93)	0.95; (0.82, 1.08)	0.85; (0.73, 0.97)	0.15; (0.13, 0.17)	0.86; (0.81, 0.90)
Electoral variance (trace∇=𝜎^2)
𝜎^2	1.17	1.17	1.63	5.607	1.462
Probability of voting for lowest valence party (party 1, 𝜌1=∑^𝑝𝑘=1exp(𝜆𝑘−𝜆1)^−1)
	Dem^b	Dem^b	Rep^b	LibDem^c	Labour^c
Est. 𝜌1; (conf. Int.^a)	𝜌Dem= 0.4; (0.35, 0.44)	𝜌Dem= 0.4; (0.35, 0.44)	𝜌rep= 0.3; (0.26, 0.35)	𝜌Lib= 0.25; (0.18, 0.32)	𝜌Lab= 0.32; (0.29, 0.32)
Convergence coefficient (𝑐≡𝑐(𝝀,𝛽,𝜎^2)=2𝛽[1−2𝜌1]𝜎^2)
Est. 𝑐; (conf. Int.^a)	0.38; (0.2, 0.65)	0.45; (0.23, 0.76)	1.1; (0.71, 1.52)	0.84; (0.51, 1.25)	0.98; (0.86, 1.10)

aConf. Int.: confidence intervals.
^bUS: Dem: Democrats; Rep: Republican.
^cUK: LibDem: Liberal Democrats.