\name{offset}
\title{Include an Offset in a Model Formula}
\usage{
offset(object)
}
\alias{offset}
\arguments{
 \item{object}{An offset to be included in a model frame}
}
\description{
  An offset is a term to be added to a linear predictor, such as in a
  generalised linear model, with known coefficient 1 rather than an
  estimated coefficient.
}
\value{
  The input value.
}
\details{
  There can be more than one offset in a model formula, but \code{-} is
  not supported for \code{offset} terms (and is equivalent to \code{+}). 
}

\seealso{
  \code{\link{model.offset}}, \code{\link{model.frame}}.
  
  For examples see \code{\link{glm}} and
  \code{\link[MASS]{Insurance}} in package \pkg{MASS}.
}
\keyword{models}