Question

I am trying to use RSM and calculate 3rd order polynomials.for quadratic below is given in Matlab Help:

stats = regstats(rsmOutput,rsmMatrix,’quadratic’,’beta’);

b = stats.beta; % Model coefficients

How can I calculate 3rd order coefficients? My reason is that with quadratic I have rsquare of 93% and my observed responses is third order.

Answer 1

        modelMatrix = [0 0 0;
            1 0 0;
            0 1 0;
            0 0 1;
            1 1 0;
            1 0 1;
            0 1 1;
            2 0 0;
            0 2 0;
            0 0 2;
            1 1 1;
            2 1 0;
            2 0 1;
            1 2 0;
            1 0 2;
            0 2 1;
            3 0 0;
            0 3 0;
            0 0 3];
           stats = regstats(rsmOutput,rsmMatrix,modelMatrix,'beta');