

   medpolish {eda}                              R Documentation

   MMeeddiiaann PPoolliisshh ooff aa MMaattrriixx

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

        Fits an additive model using Tukey's median polish pro-
        cedure.

   UUssaaggee::

        medpolish(x, eps = 0.01, maxiter = 10, trace.iter = TRUE)

        plot(medpolish.obj)
        print(medpolish.obj)

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

          x: a numeric matrix.

        eps: real number greater than 0. A tolerance for con-
             vergence: see Details.

    maxiter: the maximum number of iterations

   trace.iter: logical. Should progress in convergence be
             reported?

   medpolish.obj: object of class `medpolish'.

   DDeettaaiillss::

        The model fitted is additive (constant + rows +
        columns). The algorithm works by alternately removing
        the row and column medians, and continues until the
        proportional reduction in the sum of absolute residuals
        is less than `eps' or until there have been `maxiter'
        iterations.  The sum of absolute residuals is printed
        at each iteration of the fitting process, if
        `trace.iter' is `TRUE'.

        `medpolish' returns an object of class `medpolish' (see
        below).  There are printing and plotting methods for
        this class, which are invoked via by the generics
        `print' and `plot'.

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

        An object of class `medpolish' with the following named
        components:

    overall: the fitted constant term.

        row: the fitted row effects.

        col: the fitted column effects.

   residuals: the residuals.

       name: the name of the dataset.

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

        Tukey, J. W. (1977).  Exploratory Data Analysis, Read-
        ing Massachusetts: Addison-Wesley.

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

        `median'; `aov' for a mean instead of median decomposi-
        tion.

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

        ## Deaths from sport parachuting;  from ABC of EDA, p.224:
        deaths <-
            rbind(c(14,15,14),
                  c( 7, 4, 7),
                  c( 8, 2,10),
                  c(15, 9,10),
                  c( 0, 2, 0))
        dimnames(deaths) <- list(c("1-24", "25-74", "75-199", "200++", "NA"),
                                 paste(1973:1975))
        deaths
        (med.d <- medpolish(deaths))
        plot(med.d)
        ## Check decomposition:
        all(deaths == med.d$overall + outer(med.d$row,med.d$col, "+") + med.d$resid)

