computeMargins function

add information about voting outcomes to a rollcall object

Add summaries of each roll call vote to a rollcall object.

computeMargins(object, dropList = NULL)

Arguments

• object: an object of class rollcall
• dropList: a list (or alist) listing voting decisions, legislators and/or votes to be dropped from the analysis; see dropRollCall for details.

Details

The subsetting implied by the dropList is first applied to the rollcall object, via dropRollCall. Then, for each remaining roll call vote, the number of legislators voting Yea , Nay , and not voting are computed, using the encoding information in the codes component of the rollcall object via the convertCodes

function. The matrix of vote counts are added to the rollcall

object as a component voteMargins.

Returns

An object of class rollcall, with a component voteMargins that is a matrix with four columns: - Yea: number of legislators voting Yea

• Nay: number of legislators voting Nay

• NA: number of legislators not voting Nay

• Min: the number of legislators voting on the losing side of the roll call

Author(s)

Simon Jackman simon.jackman@sydney.edu.au

See Also

dropRollCall on specifying a dropList. The vote-specific marginals produced by this function are used by as dropRollCall, summary.ideal and predict.ideal.

Examples

data(s109)
tmp <- computeMargins(s109)
dim(tmp$voteMargins)   ## 645 by 4

tmp <- computeMargins(s109,
                     dropList=list(codes="notInLegis",lop=0))
dim(tmp$voteMargins)   ## 544 by 4