anominate (version 0.6)

anominate.sim: alpha-NOMINATE Estimation on Simulated Roll Call Matrices Generated with Normal (Gaussian) or Quadratic Utility

Description

Generates a matrix of roll call votes based on the assumption that legislators possess either normal (Gaussian) or quadratic utility functions. The roll call votes are then analyzed using the ideal point model described in Carroll, Lewis, Lo, Poole and Rosenthal, ``The Structure of Utility in Spatial Models of Voting,'' American Journal of Political Science 57(4): 1008--1028. The estimated value of the alpha parameter can be compared to the true value (1 for normal (Gaussian) utility, 0 for quadratic utility).

Usage

anominate.sim(nvotes=500, nlegis=101, seed=123345, utility="normal")

Arguments

nvotes

Number of roll call votes to be simulated

nlegis

Number of legislators to be simulated

seed

Seed for the random number generator

utility

The utility function used to generate the roll call data (``normal'' or ``quadratic'')

Value

An object of class rollcall, a list with the following components:

votes

a matrix containing voting decisions, with rows corresponding to legislators (test subjects) and columns to roll call votes (test items). Legislators (test subjects) and items (or votes) have been labeled in the dimnames attribute of this matrix, using the legis.names and/or vote.names arguments, respectively.

codes

a list with named components yea, nay, notInLegis and missing, each component a numeric vector (possibly of length 1 and possibly NA), indicating how entries in the votes component of the rollcall object should be considered. This list simply gathers up the values in the yea, nay, notInLegis and missing arguments passed to the function.

n

numeric, number of legislators, equal to dim(votes)[1]

m

numeric, number of votes, equal to dim(votes)[2]

legis.data

user-supplied data on legislators/test-subjects.

vote.data

user-supplied data on rollcall votes/test-items.

desc

any user-supplied description. If no description was provided, defaults desc defaults to NULL.

source

any user-supplied source information (e.g., a url or a short-form reference). If no description is provided, source defaults to NULL.

References

Carroll, Royce, Jeffrey B. Lewis, James Lo, Keith T. Poole and Howard Rosenthal. 2013. ``The Structure of Utility in Spatial Models of Voting.'' American Journal of Political Science 57(4): 1008--1028.

See Also

rollcall for the full documentation of a roll call object from Simon Jackman's pscl package.

Output from this function is intended for use with anominate.

Examples

# NOT RUN {
# }
# NOT RUN {
# }
# NOT RUN {
quadratic.data <- anominate.sim(utility="quadratic") 
quad_anom <- anominate(quadratic.data, dims=1, polarity=2, nsamp=200, thin=1,
	burnin=100, random.starts=FALSE, verbose=TRUE)
summary(quad_anom)

normal.data <- anominate.sim(utility="normal") 
norm_anom <- anominate(normal.data, dims=1, polarity=2, nsamp=200, thin=1, 
	burnin=100, random.starts=FALSE, verbose=TRUE)
summary(norm_anom)
# }
# NOT RUN {
# }