1          OPTIONS NONOTES NOSTIMER NOSOURCE NOSYNTAXCHECK;
 55         
 56         /******************** RepeatedNoise.sas ***********************
 57         * Participants listened to political discussions under different  *
 58         * levels of background noise. "Discrimination score" is a measure *
 59         * of how well they could tell what was being said.                *
 60         ******************************************************************/
 61         
 62         title 'Noise data';
 63         
 64         proc format;
 64       !                   value sexfmt    0 = 'Male'  1 = 'Female' ;
 NOTE: Format SEXFMT is already on the library WORK.FORMATS.
 NOTE: Format SEXFMT has been output.
 65         
 
 NOTE: PROCEDURE FORMAT used (Total process time):
       real time           0.00 seconds
       cpu time            0.00 seconds
       
 66         data loud;
 
 67              infile '/folders/myfolders/noise.data.txt';  /* Univariate data read */
 68              input ident  interest  sex  age  noise  time  discrim ;
 69              format sex sexfmt.;
 70              label interest = 'Interest in topic (politics)'
 71                    time     = 'Order of presenting noise level';
 72         
 
 NOTE: The infile '/folders/myfolders/noise.data.txt' is:
       Filename=/folders/myfolders/noise.data.txt,
       Owner Name=root,Group Name=vboxsf,
       Access Permission=-rwxrwx---,
       Last Modified=08Mar2016:00:31:45,
       File Size (bytes)=8700
 
 NOTE: 300 records were read from the infile '/folders/myfolders/noise.data.txt'.
       The minimum record length was 27.
       The maximum record length was 27.
 NOTE: The data set WORK.LOUD has 300 observations and 7 variables.
 NOTE: DATA statement used (Total process time):
       real time           0.01 seconds
       cpu time            0.00 seconds
       
 73         proc freq;
 
 74              tables sex*age*noise / norow nocol nopercent;
 75         
 
 NOTE: There were 300 observations read from the data set WORK.LOUD.
 NOTE: PROCEDURE FREQ used (Total process time):
       real time           0.07 seconds
       cpu time            0.08 seconds
       
 76         proc glm;
 
 77              title2 'Classical mixed model repeated measures';
 78              class ident age sex noise;
 79              model discrim = age|sex|noise ident(age*sex);
 80              random ident(age*sex) / test;
 81              means noise age;
 82         
 83         /* Expected mean squares show that not all the hypotheses
 84            are testable with the classical mixed model approach.
 85            SAS is buying testability of the hypotheses by assuming
 86            that you're only interested in an effect if all the
 87            higher-order interactions involving that effect are
 88            absent.
 89         
 90            Also, we can't use the covariate and it's not clear how
 91            to do multiple comparisons.  */
 92         
 
 NOTE: TYPE I EMS not available without the E1 option.
 NOTE: Means from the MEANS statement are not adjusted for other terms in the model.  For adjusted means, use the LSMEANS statement.
 NOTE: PROCEDURE GLM used (Total process time):
       real time           3.60 seconds
       cpu time            0.36 seconds
       
 93         proc mixed;
 
 94              title2 'Covariance structure (cs) with proc mixed';
 95              title3 'Replicate the classical tests';
 96              class age sex noise;
 97              model discrim = age|sex|noise;
 98              repeated / type=cs subject=ident;
 99         
 100        
 101        
 
 NOTE: Convergence criteria met.
 NOTE: PROCEDURE MIXED used (Total process time):
       real time           0.10 seconds
       cpu time            0.09 seconds
       
 102        proc mixed;
 
 103             title2 'Include covariate, multiple comparisons, contrasts';
 104             class age sex noise;
 105             model discrim = interest age|sex|noise / solution;
 106             /* solution shows the beta-hat values (interest) */
 107             repeated / type=cs subject=ident r;
 108             lsmeans age / pdiff tdiff adjust = bon;
 109             lsmeans noise / pdiff tdiff adjust = bon;
 110             contrast 'Noise Linear' noise  1 -2  1  0  0,
 111                                     noise  0  1 -2  1  0,
 112                                     noise  0  0  1 -2  1;
 113        /* In the test for departure from linearity,
 114           mu1-mu2 = mu2-mu3 => 1 -2  1  0  0
 115           mu2-mu3 = mu3-mu4 => 0  1 -2  1  0
 116           mu3-mu4 = mu4-mu5 => 0  0  1 -2  1     */
 117        
 118        /* Compare results with unknown covariance structure */
 119        
 
 NOTE: Convergence criteria met.
 NOTE: PROCEDURE MIXED used (Total process time):
       real time           0.32 seconds
       cpu time            0.31 seconds
       
 120        proc mixed cl;
 
 121             title2 'Unknown covariance structure';
 122             class age sex noise;
 123             model discrim = interest age|sex|noise;
 124             repeated / type=un subject=ident r;
 125             lsmeans age / pdiff tdiff adjust = bon;
 126             lsmeans noise / pdiff tdiff adjust = bon;
 127             contrast 'Noise Linear' noise  1 -2  1  0  0,
 128                                     noise  0  1 -2  1  0,
 129                                     noise  0  0  1 -2  1;
 130        
 131        
 132        /* Test for difference between covariance structures
 133           using a full versus reduced model approach.
 134           Difference between Likelihood Ratio chisquares is
 135           chi-squared, with df = difference of degrees of freedom.
 136           H0 is compound symmetry, alternative is unstructured.
 137           Any model for the covariance matrix is reduced compared to
 138           the unknown structure. */
 139        
 
 NOTE: Convergence criteria met.
 NOTE: PROCEDURE MIXED used (Total process time):
       real time           0.21 seconds
       cpu time            0.20 seconds
       
 140        proc iml;
 
 NOTE: IML Ready
 141             title2 'Test for difference between covariance structures';
 142             title3 'Compound symmetry versus unknown';
 143             ChiSquared = 51.44-42.90;
 143      !                                df = 14-1;
 144             pvalue = 1-probchi(ChiSquared,df);
 145             print ChiSquared df pvalue;
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 154        OPTIONS NONOTES NOSTIMER NOSOURCE NOSYNTAXCHECK;
 166