rollcall: create an object of class rollcall
In pscl: Political Science Computational Laboratory

rollcall

R Documentation

create an object of class rollcall

Description

Create a rollcall object, used for the analysis of legislative voting or, equivalently, item-response modeling of binary data produced by standardized tests, etc.

Usage

rollcall(data,
         yea=1, nay=0, missing=NA, notInLegis=9,
         legis.names=NULL, vote.names=NULL,
         legis.data=NULL, vote.data=NULL,
         desc=NULL, source=NULL)

Arguments

`data`	voting decisions (for roll calls), or test results (for IRT). Can be in one of two forms. First, `data` may be a `matrix`, with rows corresponding to legislators (subjects) and columns to roll calls (test items). `data` can also be a `list` with an element named `votes` containing the matrix described above.
`yea`	numeric, possibly a vector, code(s) for a Yea vote in the rollcall context, or a correct answer in the educational testing context. Default is 1.
`nay`	numeric, possibly a vector, code(s) for a Nay vote in the rollcall context, or an incorrect answer in the educational testing context. Default is 0.
`missing`	numeric or `NA`, possibly a vector, code(s) for missing data. Default is `NA`.
`notInLegis`	numeric or `NA`, possibly a vector, code(s) for the legislator not being in the legislature when a particular roll call was recorded (e.g., deceased, retired, yet to be elected).
`legis.names`	a vector of names of the legislators or individuals. If `data` is a `list` or `data.frame` and has a component named `legis.names`, then this will be used. Names will be generated if not supplied, or if there are fewer unique names supplied than legislators/subjects (rows of the roll call matrix).
`vote.names`	a vector of names or labels for the votes or items. If `data` is a `list` or `data.frame` and has a component named `vote.names`, then this will be used. Names will be generated if not supplied, or if there are fewer unique names supplied than votes/test-items (columns of the roll call matrix).
`legis.data`	a `matrix` or `data.frame` containing covariates specific to each legislator/test-taker; e.g., party affiliation, district-level covariates. If this object does not have the same number of rows as `data`, an error is returned.
`vote.data`	a `matrix` or `data.frame` containing covariates specific to each roll call vote or test item; e.g., a timestamp, the bill sponsor, descriptive text indicating the type of vote. If this object does not have the same number of row as the number of columns in `data`, an error is returned.
`desc`	character, a string providing an (optional) description of the data being used. If `data` is a list and contains an element named `desc`, then this will be used.
`source`	character, a string providing an (optional) description of where the roll call data originated (e.g., a URL or a short-form reference). Used in print and summary methods.

Details

See below for methods that operate on objects of class rollcall.

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`.

Examples

## generate some fake roll call data
set.seed(314159265)
fakeData <- matrix(sample(x=c(0,1),size=5000,replace=TRUE),
                   50,100)
rc <- rollcall(fakeData)
is(rc,"rollcall")        ## TRUE
rc                       ## print the rollcall object on screen

data(sc9497)             ## Supreme Court example data
rc <- rollcall(data=sc9497$votes,
               legis.names=sc9497$legis.names,
               desc=sc9497$desc)
summary(rc,verbose=TRUE)                      

## Not run: 
## s107
## could use readKH for this
dat <- readLines("sen107kh.ord")
dat <- substring(dat,37)
mat <- matrix(NA,ncol=nchar(dat[1]),nrow=length(dat))
for(i in 1:103){
  mat[i,] <- as.numeric(unlist(strsplit(dat[i],
                                        split=character(0))))
}

s107 <- rollcall(mat,
                 yea=c(1,2,3),
                 nay=c(4,5,6),
                 missing=c(7,8,9),
                 notInLegis=0,
                 desc="107th U.S. Senate",
                 source="http://voteview.ucsd.edu")
summary(s107)

## End(Not run)

pscl documentation built on May 29, 2024, 9:09 a.m.