\name{diversi.gof}
\alias{diversi.gof}
\title{Tests of Constant Diversification Rates}
\usage{
diversi.gof(x, null = "exponential", z = NULL)
}
\arguments{
  \item{x}{a numeric vector with the branching times.}
  \item{null}{a character string specifying the null distribution for
    the branching times. Only two choices are possible: either
    \code{"exponential"}, or \code{"user"}.}
  \item{z}{used if \code{null = "user"}; gives the expected distribution
    under the model.}
}
\description{
  This function computes two tests of the distribution of branching
  times using the Cramťr-von Mises and Anderson-Darling goodness-of-fit
  tests. By default, it is assumed that the diversification rate is
  constant, and an exponential distribution is assumed for the branching
  times. In this case, the expected distribution under this model is
  computed with a rate estimated from the data. Alternatively, the user
  may specify an expected cumulative density function (\code{z}): in this
  case, \code{x} and \code{z} must be of the same length.
}
\details{
  The Cramťr-von Mises and Anderson-Darling tests compare the empirical
  density function (EDF) of the observations to an expected cumulative
  density function. By contrast to the Kolmogorov--Smirnov test where
  the greatest difference between these two functions is used, in both
  tests all differences are taken into account.

  The distributions of both test statistics depend on the null
  hypothesis, and on whether or not some parameters were estimated from
  the data. However, these distributions are not known precisely and
  critical values were determined by Stephens (1974) using
  simulations. These critical values were used for the present function.
}
\value{
  A NULL value is returned, the results are simply printed.
}
\references{
  Paradis, E. (1998) Testing for constant diversification rates using
  molecular phylogenies: a general approach based on statistical tests
  for goodness of fit. \emph{Molecular Biology and Evolution},
  \bold{15}, 476--479.

  Stephens, M. A. (1974) EDF statistics for goodness of fit and some
  comparisons. \emph{Journal of American Statistical Association},
  \bold{69}, 730--737.
}
\author{Emmanuel Paradis \email{paradis@isem.univ-montp2.fr}}
\seealso{
  \code{\link{branching.times}}, \code{\link{diversi.time}}
  \code{\link{ltt.plot}}, \code{\link{birthdeath}}
}
\keyword{univar}