(* PS2.3, using DATA2-2 -- on covariance and corr. coeff. - Section 2.5 *)
genr x = colgpa
genr y = hsgpa
genr n = $nobs
(* mean of colgpa *)			
genr xbar = mean(x)
(* s.d. of colgpa *)			
genr sx = sd(x)
(* mean of hsgpa *)			
genr ybar = mean(y)
(* s.d. of hsgpa *)			
genr sy = sd(y)
(* cross product of deviation from mean *)	
genr sxy = (x-xbar)*(y-ybar)
(* compute covariance *)		
genr covxy = sum(sxy)/(n-1)
(* compute correlation coefficient *)	
genr corxy = covxy/(sx*sy)
(* reset sample range *)		
smpl 1 1
(* print values *)		
print xbar sx ybar sy covxy corxy 
(* reset sample range *)                
smpl 1 427
(* same with the corr command *)	
corr x y 
(* summary statistics *)                
summary x y
