

   CCoommppoouunndd SSyymmmmeettrryy CCoorrrreellaattiioonn SSttrruuccttuurree

        corCompSymm(value, form)

   AArrgguummeennttss::

      value: the correlation between any two correlated obser-
             vations. Defaults to 0.

       form: a one sided formula of the form `~ t', or code{~ t
             | g}, specifying a time covariate `t' and,
             optionally, a grouping factor `g'. When a grouping
             factor is present in `form', the correlation
             structure is assumed to apply only to observations
             within the same grouping level; observations with
             different grouping levels are assumed to be uncor-
             related. Defaults to `~ 1', which corresponds to
             using the order of the observations in the data as
             a covariate, and no groups.

   DDeessccrriippttiioonn::

        This function is a constructor for the `corCompSymm'
        class, representing a compound symmetry structure cor-
        responding to uniform correlation. Objects created
        using this constructor need to be later initialized
        using the appropriate `initialize' method.

   VVaalluuee::

        an object of class `corCompSymm', representing a com-
        pound symmetry correlation structure.

   AAuutthhoorr((ss))::

        Jose Pinheiro and Douglas Bates

   RReeffeerreenncceess::

        Milliken, G. A. and Johnson, D. E. (1992) "Analysis of
        Messy Data, Volume I: Designed Experiments", Van Nos-
        trand Reinhold.

   SSeeee AAllssoo::

        `initialize.corStruct'

   EExxaammpplleess::

        library(lme)
        ## covariate is observation order and grouping factor is Subject
        cs1 <- corCompSymm(0.5, form = ~ 1 | Subject)

