22S:152  Homework 10
      Fall 2002
      Due Mon. 11/18 in class

      Under datasets on the course web page, please find the files

            pprv.dat
            pprv.info  (description of dataset; read this to understand
                        the problem)

          1.  Is this data balanced or unbalanced?

          2.  Use SAS to carry out the necessary analyses.  Then report
              your answers to the questions below.  Turn in your SAS output,
              with notations to show which parts you used to answer each
              question.

              a.   Obtain summary statistics on
                   the data and check the assumptions of the statistical
                   procedure you will be using for part b.  Do the assumptions
                   appear to be approximately met?
  
              b.   We are interested in three separate populations of
                   patients with idiopathic pulmonary fibrosis: those who
                   never smoked, those who smoked previously, and those
                   who are current smokers.

                   Test the hypothesis that the means of percent predicted
                   volume are the same in all three populations.  What do
                   you conclude (at the .05 significance level)?


              

            
              c.   If you found that there were any real differences among
                   the population means, determine which pairs are different.
                   Make sure that your overall chance of type I error for this
                   process is not greater than .05.


                   (1)  Are you being asked to control comparisonwise
                        error or experimentwise error?


                   (2)  Which pair(s) of population means do you conclude 
                        are different?