x=[1 7 26 6 60 ;
   1 1 29 15 52 ;
    1 11 56 8 20 ;
    1 11 31 8 47;
    1 7 52 6 33;
    1 11 55 9 22;
    1 3 71 17 6;
   1  1 31 22 44;
    1 2 54 18 22;
    1 21 47 4 26;
    1 1 40 23 34;
   1  11 66 9 12;
   1  10 68 8 12];
y=[78.5 74.3 104.3 87.6 95.9 109.2 102.7 72.5 93.1 115.9 83.8 113.3 109.4]';
[b, bint,r,rint,stats] = regress(y,x);
rcoplot(r,rint);

X1 = x(:,2);
X2 = x(:,3);
X3 = x(:,4);
X4 = x(:,5);
X = [X1 X2 X3 X4];
stepwise(X,y)