

   RRaannddoomm EEffffeeccttss SSttrruuccttuurree

        reStruct(object, pdClass, RML, data)

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

     object: any of the following: (i) a one-sided formula of
             the form `~x1+...+xn | g1/.../gm', with
             `x1+...+xn' specifying the model for the random
             effects and `g1/.../gm' the grouping structure
             (`m' may be equal to 1, in which case no `/' is
             required). The random effects formula will be
             repeated for all levels of grouping, in the case
             of multiple levels of grouping; (ii) a list of
             one-sided formulas of the form `~x1+...+xn | g',
             with possibly different random effects models for
             each grouping level. The order of nesting will be
             assumed the same as the order of the elements in
             the list; (iii) a one-sided formula of the form
             `~x1+...+xn', or a `pdMat' object with a formula
             (i.e. a non-`NULL' value for `formula(object)'),
             or a list of such formulas or `pdMat' objects. In
             this case, the grouping structure formula will be
             derived from the data used to to fit the mixed-
             effects model, which should inherit from class
             `groupedData'; (iv) a named list of formulas or
             `pdMat' objects as in (iii), with the grouping
             factors as names. The order of nesting will be
             assumed the same as the order of the order of the
             elements in the list; (v) an `reStruct' object.

    pdClass: an optional character string with the name of the
             `pdMat' class to be used for the formulas in
             `object'. Defaults to `"pdSymm"' which corresponds
             to a general positive-definite matrix.

        RML: an optional logical value. If `TRUE', the associ-
             ated mixed-effects model will be fitted using
             restricted maximum likelihood; else, if `FALSE',
             maximum likelihood will be used. Defaults to
             `FALSE'.

       data: an optional data frame in which to evaluate the
             variables used in the random effects formulas in
             `object'. It is used to obtain the levels for
             `factors', which affect the dimensions and the
             row/column names of the underlying `pdMat'
             objects. If `NULL', no attempt is made to obtain
             information on `factors' appearing the random
             effects model. Defaults to parent frame from which
             the function was called.

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

        This function is a constructor for the `reStruct'
        class, representing a random effects structure and con-
        sisting of a list of `pdMat' objects, plus a `settings'
        attribute containing information for the optimization
        algorithm used to fit the associated mixed-effects
        model.

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

        an object inheriting from class `reStruct', represent-
        ing a random effects structure.

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

        Jose Pinheiro and Douglas Bates

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

        `pdMat', `lme', `groupedData'

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

        library(lme)
        data(Pixel)
        rs1 <- reStruct(list(Dog = ~day, Side = ~1), data = Pixel)
        rs1

