fig2_6

 Local Regression and Likelihood, Figure 2.6.

 Influence and variance functions.

0001 % Local Regression and Likelihood, Figure 2.6.
0002 %
0003 % Influence and variance functions.
0004 
0005 load ethanol;
0006 d = [2 3];
0007 a = [0.49 0.59];
0008 main = {'Local Quadratic','Local Cubic'};
0009 f=['a','b'];
0010 for (i=1:2)
0011   figure('Name', sprintf( 'figure2_6%c: Influence and variance functions', f(i) ) );
0012   fit = locfit(E,NOx,'nn',a(i),'deg',d(i),'ev','grid','mg',100);
0013   vecr(fit)
0014   plot(E,zeros(88,1),'o');
0015   title(main{i});
0016   hold on;
0017   lfplot(fit,'what','infl');
0018   lfplot(fit,'what','vari','--');
0019   xlabel('Equivalence Ratio');
0020   ylabel('Influence');
0021   legend('Data','Influence Function','Variance Function');
0022   hold off;
0023 end;