/* electric.sas */
options ls=72 ps=60;
data elec;
   infile 'electric.dat';
   input date day $ temp load;
   period = 'weekday';
   if day = 'Sun' then period = 'sun'; 
   if day = 'Sat' then period = 'sat';
   indicate = period;
   if period = 'sun' then indicate = 'u'; 
   if date=5 then period = 'sun'; 
   if date=5 then indicate = 'hol';
   x0=1;
   week = (period = 'weekday');
   sat = (period = 'sat');
   sun = (period = 'sun');
   end = sat+sun;
   weektemp = temp*week;
   sattemp = temp*sat;
   suntemp = temp*sun;
proc plot data=elec;
   plot load*temp=indicate;
title 'electricity load data';
proc print data=elec;
   var date day period weektemp sattemp suntemp;
proc print data=elec;
   var date day period week sat sun; 
proc glm data=elec;
   model load=week sat sun weektemp sattemp suntemp/
              noint ss1 ss2;
      contrast 'parallel lines' weektemp 1 sattemp -1,
                                sattemp 1 suntemp -1;
      output out=new1 predicted=yhat residual=resid lcl=clpl
             ucl=clpu lclm=clml uclm=clmu;
title '3 separate lines: weekday, Saturday, Sunday';
proc print data=new1;
   var period date temp load clml clmu clpl clpu yhat resid;
proc plot data=new1;
   plot resid*temp=indicate / vref=0;
   plot resid*date=indicate / vref=0;
proc univariate data=new1 plot normal;
     var resid;
proc rank data=new1 normal=blom out=new1r;
     var resid;
     ranks normsc;
proc plot data=new1r;
     plot resid*normsc;
proc glm data=elec;
   model load=week sat sun temp/noint ss1 ss2;
      estimate 'dist betw week sat' week 1 sat -1;
      estimate 'dist betw sat sun'  sat 1 sun -1;
      output out=new2 predicted=yhat residual=resid lcl=clpl
             ucl=clpu lclm=clml uclm=clmu;
title '3 parallel lines: weekday, Saturday, Sunday';
proc print data=new2;
   var period date temp load clml clmu clpl clpu yhat resid;
proc plot data=new2;
   plot resid*temp=indicate / vref=0;
   plot resid*date=indicate / vref=0;
proc univariate data=new2 plot normal;
     var resid;
proc rank data=new2 normal=blom out=new2r;
     var resid;
     ranks normsc;
proc plot data=new2r;
     plot resid*normsc;
proc glm data=elec;
   model load=week end temp/noint ss1 ss2 clparm;
      estimate 'dist betw week end' week 1 end -1;
      output out=new3 predicted=yhat residual=resid lcl=clpl
             ucl=clpu lclm=clml uclm=clmu;
title '2 parallel lines: weekday, weekend';
proc print data=new3;
   var period date temp load clml clmu clpl clpu yhat resid;
proc plot data=new3;
   plot resid*temp=indicate / vref=0;
   plot resid*date=indicate / vref=0;
proc univariate data=new3 plot normal;
     var resid;
proc rank data=new3 normal=blom out=new3r;
     var resid;
     ranks normsc;
proc plot data=new3r;
     plot resid*normsc;
proc glm data=elec;
   model load=x0 temp/noint ss1 ss2;
      output out=new4 predicted=yhat residual=resid lcl=clpl
             ucl=clpu lclm=clml uclm=clmu;
title 'single line for all days';
proc print data=new4;
   var period date temp load clml clmu clpl clpu yhat resid;
proc plot data=new4;
   plot resid*temp=indicate / vref=0;
   plot resid*date=indicate / vref=0;
run;