Resources

Computing the Classical T-Square Statistic

/****************************************************************/
/*          S A S   S A M P L E   L I B R A R Y                 */
/*                                                              */
/*    NAME: MVPMDEX2                                            */
/*   TITLE: Computing the Classical T-Square Statistic          */
/* PRODUCT: QC                                                  */
/*  SYSTEM: ALL                                                 */
/*    KEYS: T-Square Statistic                                  */
/*   PROCS: MVPMODEL                                            */
/*    DATA:                                                     */
/*                                                              */
/* SUPPORT: saswgr                                              */
/*     REF: PROC MVPMODEL, Example 2                            */
/*                                                              */
/****************************************************************/

data flightDelaysNE;
   input  AA CO DL F9 FL NW UA US WN;
   datalines;
15.7  7.1  8.6  6.3 14.6  6.2  7.0 11.0  6.4
16.0 19.4 10.7  6.4 19.0  6.1  8.3 14.4 14.2
14.5  1.5  5.4 13.3 13.6  9.7 16.6  7.5  9.9
12.4 14.3  5.8  0.7 11.8 20.1 11.2  8.6  8.1
19.8 27.6  7.3 16.1 13.3 14.8 39.9 16.4  9.7
20.5 12.2  0.2 -4.8  3.7 14.2 41.7  4.9  9.2
 8.3  4.1  3.4  4.2 -2.3  6.3 24.9  8.7  4.4
 4.7 14.1  1.8 18.1 -1.9 10.2  5.4  5.8  3.7
16.7 15.0  3.5 11.8  0.8  7.3 11.1  7.2  5.1
 6.2  0.6  2.6  9.3  3.0  4.0  4.0  6.9  1.9
 6.9  8.4  0.3  1.7 -1.1 10.4  8.7  9.4  4.6
16.5  7.7  2.5  8.1  4.2 11.0 18.4  6.2  2.4
21.2 10.2  5.6  1.1 18.7  9.2 35.0 49.7 35.9
22.5 30.0 26.1 14.2 41.5 46.2 43.6 75.5 34.1
62.7 60.4 39.5 27.6 44.9 27.9 51.5 64.7 38.2
31.3 41.4 23.1 40.2 19.3 19.7 28.3 40.4 17.3

proc mvpmodel data=flightDelaysNE ncomp=all plots=none out=mvpout;
   var AA CO DL F9 FL NW UA US WN;
run;

proc iml;
   use flightDelaysNE;
   read all into x;
   n = nrow(x);
   p = ncol(x);
   xc = x-x[:,]; /* Create a centered data set*/
   ss = xc[##,];  /* Compute sum of squares */
   std=sqrt(ss/(n-1));  /* Compute standard deviations */
   std_x = xc/std;  /* Create a standardized data set*/
   S= cov(std_x);  /* Compute covariance of standardized data*/
   tsq = J(n,1,.);
   do i = 1 to n;
   /* Compute the classical T2 statistic using quadratic form */
      tsq[i] = std_x[i,]*inv(S)*std_x[i,]`;
   end;
   varnames = "tsq";
   create classicTsq from tsq [colname = varnames];
   append from tsq;
quit;

data mvpTsq;
   set mvpOut(rename=(_TSQUARE_=tsq));
   keep tsq;
run;

proc compare base=classicTsq compare=mvpTsq
             method=relative briefsummary;
run;