R Dataset / Package pscl / unionDensity


On this Picostat.com statistics page, you will find information about the unionDensity data set which pertains to cross national rates of trade union density. The unionDensity data set is found in the pscl R package. You can load the unionDensity data set in R by issuing the following command at the console data("unionDensity"). This will load the data into a variable called unionDensity. If R says the unionDensity data set is not found, you can try installing the package by issuing this command install.packages("pscl") and then attempt to reload the data. If you need to download R, you can go to the R project website. You can download a CSV (comma separated values) version of the unionDensity R data set. The size of this file is about 805 bytes.

cross national rates of trade union density


Cross-national data on relative size of the trade unions and predictors, in 20 countries. Two of the predictors are highly collinear, and are the source of a debate between Stephens and Wallerstein (1991), later reviewed by Western and Jackman (1994).




  • unionnumeric, percentage of the total number of wage and salary earners plus the unemployed who are union members, measured between 1975 and 1980, with most of the data drawn from 1979

  • leftnumeric, an index tapping the extent to which parties of the left have controlled governments since 1919, due to Wilensky (1981).

  • sizenumeric, log of labor force size, defined as the number of wage and salary earners, plus the unemployed

  • concennumeric, percentage of employment, shipments, or production accounted for by the four largest enterprises in a particular industry, averaged over industries (with weights proportional to the size of the industry) and the resulting measure is normalized such that the United States scores a 1.0, and is due to Pryor (1973). Some of the scores on this variable are imputed using procedures described in Stephens and Wallerstein (1991, 945).


Pryor, Frederic. 1973. Property and Industrial Organization in Communist and Capitalist Countries. Bloomington: Indiana University Press.

Stephens, John and Michael Wallerstein. 1991. Industrial Concentration, Country Size and Trade Union Membership. American Political Science Review 85:941-953.

Western, Bruce and Simon Jackman. 1994. Bayesian Inference for Comparative Research. American Political Science Review 88:412-423.

Wilensky, Harold L. 1981. Leftism, Catholicism, Democratic Corporatism: The Role of Political Parties in Recemt Welfare State Development. In The Development of Welfare States in Europe and America, ed. Peter Flora and Arnold J. Heidenheimer. New Brunswick: Transaction Books.


Jackman, Simon. 2009. Bayesian Analysis for the Social Sciences. Wiley: Hoboken, New Jersey.


        "log Size of\nLabor Force",
        r <- cor(x,y)
ols <- lm(union ~ left + size + concen,

Dataset imported from https://www.r-project.org.

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Attachment Size
dataset-39173.csv 805 bytes
Dataset License
GNU General Public License v2.0
Documentation License
GNU General Public License v2.0