(Weighted) Party System Dispersion
Polarization: ideological elite
Data: marpor
Use Cases: @ezrow_variance_2007 @dreyer_does_2019,
Description
Ezrow (2007) proposed the (Weighted) Party System Dispersion measure, which is basically a weighted standard deviation formula. Both Ezrow (2007) and Dreyer and Bauer (2019) use MARPOR data to measure party positions, but in principle it can be used with other datasets that contain the required information, i.e. party positions.
Operationalization
The (weighted) party system dispersion is measured as follows:
$Weighted~party~system~dispersion = \sqrt{\sum_{j=1} VS_{j} (P_{jk} - \bar{P}_k)^2}$
where $P_{jk}$ is the ideological position of party $j$ in country $k$ and $\bar{P_k}$ is the weighted average of the left-right ideological positions of all parties in country year $k$. $VS_j$ is the vote share of party $j$ in the last national election.
polaR
# Import Data
cses_imd <- polaR_import(source = "cses_imd",
path = "path/to/dataset.dta")
# Where different issue dimensions are available, 'issue' can be issued to specify it
cses_imd <- dispersion(cses_imd,
issue = "leftright")
Visualization
Use cases
Publication that use this measure:
| Title | Authors |
|---|---|
| Does voter polarisation induce party extremism? | Dreyer and Bauer (2019) |
| The Variance Matters | Ezrow (2007) |