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\name{percentages}
\alias{percentages}
\alias{percentages.table}
\alias{percentages.formula}
\alias{percentages.default}
\alias{percentages.data.frame}
\alias{percentages.list}
\alias{as.data.frame.percentage.table}
\alias{as.data.frame.xpercentage.table}
\title{
Easy Creation of Tables of Percentages
}
\description{
The generic function \code{percentages} and its methods
create one- or multidimensional tables of percentages. As such,
the function \code{percentages} can be viewed as a convenience
interface to \code{\link{prop.table}}. However, it also
allows to obtain standard errors and confidence intervals.
}
\usage{
percentages(obj, \dots)
\method{percentages}{table}(obj,
by=NULL, which=NULL, se=FALSE, ci=FALSE, ci.level=.95, \dots)
\method{percentages}{formula}(obj,
data=parent.frame(), weights=NULL, \dots)
\method{percentages}{default}(obj,
weights=NULL, \dots)
\method{percentages}{data.frame}(obj,
weights=NULL, \dots)
\method{percentages}{list}(obj,
weights=NULL, \dots)
\method{as.data.frame}{percentage.table}(x, \dots)
\method{as.data.frame}{xpercentage.table}(x, \dots)
}
\arguments{
\item{obj}{an object; a contingency table or a formula. If
it is a formula, its left-hand side determines the factor
or combination of factors for which percentages are
computed while its right-hand side determines the
factor or combination of factors that define the
groups within which percentages are computed.}
\item{by}{a character vector with the names of the
factor variables that define the groups within which percentages
are computed. Percentages sum to 100 within combination
of levels of these factors.}
\item{which}{a character vector with the names of the
factor variables for which percentages
are computed.}
\item{se}{a logical value; determines whether standard
errors are computed.}
\item{ci}{a logical value; determines whether confidence
intervals are computed. Note that the confidence intervals
are for infinite (or very large) populations.}
\item{ci.level}{a numerical value, the required confidence level of
the confidence intervals.}
\item{data}{a contingency table (an object that inherits from "table")
or a data frame or an object coercable into a data frame.}
\item{weights}{an optional vector of weights. Should be NULL or a
numeric vector.}
\item{\dots}{Further arguments passed on to the
"table" method of \code{percentages} or ignored in case of
a call to \code{as.data.frame}.}
\item{x}{an object coerced into a data frame.}
}
\value{
An array that inherits classes "percentage.table" and "table". If
\code{percentages} was called with \code{se=TRUE} or \code{ci=TRUE}
then the result additionally inherits class "xpercentage.table".
}
\examples{
percentages(UCBAdmissions)
# Three equivalent ways to create the same table of conditional
# percentages
percentages(Admit~Gender+Dept,data=UCBAdmissions)
percentages(UCBAdmissions,by=c("Gender","Dept"))
percentages(UCBAdmissions,which="Admit")
# Percentage table as data frame
as.data.frame(percentages(Admit~Gender+Dept,data=UCBAdmissions))
# Standard errors and confidence intervals
percentages(Admit~Dept,data=UCBAdmissions,se=TRUE)
percentages(Admit~Dept,data=UCBAdmissions,ci=TRUE)
(p<- percentages(Admit~Dept,data=UCBAdmissions,ci=TRUE,se=TRUE))
# An extended table of percentages as data frame
as.data.frame(p)
# A table of percentages of a factor
percentages(iris$Species)
UCBA <- as.data.frame(UCBAdmissions)
percentages(UCBA$Admit,weights=UCBA$Freq)
percentages(UCBA,weights=UCBA$Freq)
}
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