MATLAB: What is the order of the regression parameters for a full quadratic model in Matlab

design of experimentsregression analysis

I have a 4 factor model and I used the regstat function in matlab to determine the coefficients but I do not know the order in which Matlab outputs the parameters. Textbook references is in this order: Constant, Linear,Interaction and quadratic terms. I am wondering if the order is the same for Matlab.

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"help regstats" in my version points to "help x2fx" for the order of terms. The latter confirms that your order is correct, and it also defines the order of the interaction terms.

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MATLAB: Regstats model equation

Hi Dave, you can use x2fx() to figure out what order your terms appear in.

MATLAB: Regression

Here is an example:

x = (1:20)';
y = 2 + 3*x + 7*rand(20,1);
model = fit(x,y,'poly1')
figure
plot(model,x,y)

The plot command here is an "overloaded" method for cfit objects (the output of the fit command). The documentation is here: http://www.mathworks.com/help/toolbox/curvefit/plot.html

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MATLAB: Regstats model equation

MATLAB: Regression

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