

   DDaattaa sseett ooff oozzoonnee mmeeaassuurreemmeennttss aatt 2200 CChhiiccaaggoo mmoonniittoorriinngg ssttaa--
   ttiioonnss..

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

          x: Longitude-latitude postion of monitoring stations.

          y: Average daily ozone values over 1987 summer.

   SSUUMMMMAARRYY::

        The `ozone' data is a list of two components, x and y.
        The x component is longitude and latitude position of
        each of the 20 Chicago monitoring stations. The y com-
        ponent is the average daily ozone values over the time
        period 6/3/87-8/30/87.

   ""DDAATTAA::

        This data set is a list containing the following compo-
        nents:

   SSOOUURRCCEE::

        AIR, the EPA air quality data base.

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

        tps, krig, nnreg

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

        tps(ozone$x, ozone$y) -> fit # fitting a surface to ozone measurements.
        plot(fit) # plots fit and residuals

