1          OPTIONS NONOTES NOSTIMER NOSOURCE NOSYNTAXCHECK;
 72         
 73         /* pain2.sas (2018 version) */
 74         title 'Covariance structure repeated measures analysis of the pain data';
 75         
 76         /* Read data from an old .xls spreadsheet */
 77         proc import datafile="/folders/myfolders/441s18/Lecture/Pain.xls"
 78                     out=ouch0 dbms=xls replace;
 79                     getnames=yes;
 
 NOTE: The import data set has 10 observations and 7 variables.
 NOTE: WORK.OUCH0 data set was successfully created.
 NOTE: PROCEDURE IMPORT used (Total process time):
       real time           0.02 seconds
       cpu time            0.01 seconds
       
 80         proc print;
 
 81         
 82         /*           Dose 1         Dose 2         Dose 3
 83                      ------         -----          ------
 84         Drug 1     Drug1Dose1     Drug1Dose2     Drug1Dose3
 85         Drug 2     Drug2Dose1     Drug2Dose2     Drug2Dose3   */
 86         
 
 NOTE: There were 10 observations read from the data set WORK.OUCH0.
 NOTE: PROCEDURE PRINT used (Total process time):
       real time           0.07 seconds
       cpu time            0.08 seconds
       
 87         data hurt;
 
 88              set ouch0;
 89              /* Need each response on a separate line for proc mixed. */
 90              array response{6} Drug1Dose1 -- Drug2Dose3;
 91              index = 0;
 92              do drug = 1 to 2;
 93                  do dose = 1 to 3;
 94                      index = index + 1;
 95                      pain = response{index};
 96                      output;
 97                  end;
 98              end;
 99              keep patient drug dose pain;
 100        
 
 NOTE: There were 10 observations read from the data set WORK.OUCH0.
 NOTE: The data set WORK.HURT has 60 observations and 4 variables.
 NOTE: DATA statement used (Total process time):
       real time           0.00 seconds
       cpu time            0.01 seconds
       
 101        proc print data = hurt (obs=12); /* Just the first 12 lines */
 
 102        
 
 NOTE: There were 12 observations read from the data set WORK.HURT.
 NOTE: PROCEDURE PRINT used (Total process time):
       real time           0.05 seconds
       cpu time            0.06 seconds
       
 103        proc mixed data=hurt;
 
 104             title2 'Unknown covariance structure';
 105             class drug dose;
 106             model pain = drug|dose;
 107             repeated / type=un subject=patient;
 108             /* Pairwise comparisons of marginal means for Dose */
 109             lsmeans dose / pdiff tdiff adjust = bon;
 110        run;
 
 NOTE: Convergence criteria met.
 NOTE: PROCEDURE MIXED used (Total process time):
       real time           0.24 seconds
       cpu time            0.23 seconds
       
 
 111        
 112        proc mixed data=hurt;
 113             title2 'Compound symmetry';
 114             class drug dose;
 115             model pain = drug|dose;
 116             repeated / type=cs subject=patient;
 117             lsmeans dose / pdiff tdiff adjust = bon;
 118        run;
 
 NOTE: Convergence criteria met.
 NOTE: PROCEDURE MIXED used (Total process time):
       real time           0.20 seconds
       cpu time            0.18 seconds
       
 
 119        
 120        /* F-tests from cs do not match up with the proc glm univariate tests
 121           in pain1.sas that are produced as a by-product of the multivariate
 122           approach. If you know how to read it, output from the code below
 123           shows that for this (simple and quite common) example, exact classical
 124           F-tests for the main effects do not exist unless the interaction is
 125           assumed to be absent. The proc mixed tests match what you get by making
 126           this assumption. It seems that the "by-product" univariate repeated
 127           measures analysis produced by proc glm is doing something else. I do
 128           not know exactly what it is doing, except that in every example I can
 129           find where all the classical tests DO exist, proc glm matches them.
 130           If we want the compound symmetry assumption, we will use proc mixed. */
 131        
 132        proc glm data=hurt noprint; /* Not showing the output */
 133             title2 'Trying classical the old fashioned way';
 134             class patient drug dose;
 135             model pain = patient drug|dose;
 136             random patient / test;
 137        run;
 
 138        
 139        
 140        
 141        OPTIONS NONOTES NOSTIMER NOSOURCE NOSYNTAXCHECK;
 154