% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/compare.R
\name{gb_compare}
\alias{gb_compare}
\title{Compare multiple appraisal options}
\usage{
gb_compare(..., by = "npv")
}
\arguments{
\item{...}{\code{gb_appraisal} objects to compare. Pass as named
arguments to control labels (e.g. \code{do_minimum = app1}).}

\item{by}{Character. Ranking criterion: one of \code{"npv"} (default)
or \code{"bcr"}.}
}
\value{
A \code{gb_comparison} object: a list with class
\code{c("gb_comparison", "list")} and elements \code{options},
\code{summary_table}, \code{preferred_npv}, \code{preferred_bcr}, \code{by}.
}
\description{
Builds a side-by-side comparison of two or more \code{gb_appraisal}
objects. Returns a \code{gb_comparison} with a ranked summary table
and the preferred option under both NPV and BCR criteria.
}
\details{
Every Green Book economic case must compare at least Do Minimum
against one or more Do Something options. \code{gb_compare()}
standardises the comparison: NPV, BCR, EANC, PV costs, PV benefits,
and rank under both NPV and BCR. The \code{summary()} method renders a
one-page table suitable for a Five Case Model economic case.
}
\examples{
do_minimum <- gb_appraise(c(50, 0, 0, 0, 0), c(0, 20, 20, 20, 20))
do_max <- gb_appraise(c(150, 0, 0, 0, 0), c(0, 50, 50, 50, 50))
gb_compare(do_minimum = do_minimum, do_max = do_max)
}
\references{
HM Treasury (2022). The Green Book: Central Government Guidance
on Appraisal and Evaluation, chapter on options analysis.
}
\seealso{
\code{\link[=gb_appraise]{gb_appraise()}}, \code{\link[=gb_economic_case]{gb_economic_case()}}.

Other appraisal: 
\code{\link{gb_appraise}()},
\code{\link{gb_economic_case}()},
\code{\link{gb_place_based}()},
\code{\link{gb_progression}()},
\code{\link{gb_risk_register}()},
\code{\link{gb_sensitivity_ob}()},
\code{\link{gb_validate}()}
}
\concept{appraisal}
