** This file demonstrates how to use Minitab to do a chi-squared QQ-plot 
** to check the multivariate normal assumption.
**

 MTB > read 'T4-3.DAT' c1-c4
 Entering data from file: T4-3.DAT
      30 rows read.
 MTB > let c1=c1-mean(c1)
 MTB > let c2=c2-mean(c2)
 MTB > let c3=c3-mean(c3)
 MTB > let c4=c4-mean(c4)
 MTB > copy c1-c4 m1
 MTB > covariance c1-c4 m3 
 MTB > inverse m3 m4
 MTB > multiply m1 m4 m5
 MTB > copy m5 c11-c14
 MTB > let c15=c1*c11+c2*c12+c3*c13+c4*c14
 MTB > print c15
 
 C15     
    0.6000    5.4770    7.6166    5.2076    1.3981    2.2191    4.9883 
    1.4877   12.2648    0.7665    1.9308    0.4635    2.6959    0.1296 
    1.0792   16.8474    3.5018    3.9901    1.3632    1.4650    9.8980 
    5.0557    0.7962    2.5386    4.5768    3.3980    2.3816    2.9952 
    6.2838    2.5838 
 
 MTB > sort c15 c16

 MTB > set c17
 DATA> 1:30     
 DATA> end
 
 MTB > let c17=(c17-0.5)/30
 MTB > invcdf c17 c18;
 SUBC> chisq 4.
 MTB > 
 MTB > plot c16*c18