oc {oc} | R Documentation |
oc
is the function that takes a rollcall
object and estimates nonmetric
Optimal Classification scores with them.
oc(rcObject, dims=2, minvotes=20, lop=0.025, polarity, verbose=FALSE)
rcObject |
An object of class rollcall , from Simon Jackman's pscl package. |
dims |
integer, number of dimensions to estimate. Must be nonnegative and cannot exceed 10 dimensions. |
minvotes |
minimum number of votes a legislator must vote in for them to be analyzed. |
lop |
A proportion between 0 and 1, the cut-off used for excluding lopsided
votes, expressed as the proportion of non-missing votes on the minority side.
The default, lop=0.025 , eliminates votes where the minority is smaller
than 2.5
overwrites the lopsided attribute in the RC object inputted. |
polarity |
a vector specifying the legislator in the data set who is conservative on
each dimension. For example, c(3,5) indicates legislator 3 is conservative
on dimension 1, and legislator 5 is conservative on dimension 2.
Alternatively, polarity can be specified as a string for legislator names
found in legis.names (ie. c("Bush", "Gore") ) if every legislative name in
the data set is unique. Finally, polarity can be specified as a list (ie.
list("cd",c(4,5)) ) where the first list item is a variable from the roll
call object's legis.data , and the second list item is a conservative
legislator on each dimension as specified by the first list item.
list("cd",c(4,5)) thus specifies the legislators with congressional
district numbers of 4 and 5. |
verbose |
logical, indicates whether bills and legislators to be deleted should be printed while data is being checked before ideal points are estimated. |
An object of class OCobject
, with elements as follows:
legislators |
data frame, containing all data from the old perf25.dat file about
legislators. For a typical ocObject run with an ORD file read using
readKH , it will contain the following:
|
rollcalls |
data frame, containing all data from the old perf21.dat file about
bills. For a typical OCobject object run with an ORD file read
using readKH , it will contain the following:
|
dimensions |
integer, number of dimensions estimated. |
eigenvalues |
A vector of roll call eigenvalues. |
fits |
A vector of length 2 with the classic measures of fit, containing the percent correct classification and the APRE. |
Keith Poole kpoole@ucsd.edu
Jeffrey Lewis jblewis@ucla.edu
James Lo jameslo@ucla.edu
Royce Carroll rcarroll@ucsd.edu
Keith Poole. 2000. 'Non-parametric Unfolding of Binary Choice Data.' Political Analysis, 8(3):211-237
Keith Poole. 2005. 'Spatial Models of Parliamentary Voting.' Cambridge: Cambridge University Press.
Keith Poole. http://voteview.ucsd.edu/
'plot.OCobject','summary.OCobject'.
#This data file is the same as reading file using: #sen90 <- readKH("ftp://voteview.com/sen90kh.ord") #All ORD files can be found on www.voteview.com data(sen90) summary(sen90) result<-oc(sen90,dims=2,polarity=c(7,2)) summary(result) plot(result)