# 3D plots - surface response for 4 variables central composite design

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Hello,

I need to generate a surface response plot that correlates 3 independent variables (x, y, z) to my output A. I ran ANOVA on my central composite design and obtained a model that looks like:

f(A) = c1x2 + c2y2 + c3z2 +c4xy+c5xz+c6yz+c7 where c1, c2, c3...c7 c4 are constants.

How can I plot x vs y vs z so that the SURFACE is A and values shown incolours I can only plot2 independent variables at a time!

Thanks!!

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Hello, the custom function plots under Graphs|3D XYZ can only have two variables(e.g. x and y) on the right side of the customized function equation, that's what a typical 3D plot does. If you have 3 variables on the right side of the customized function, it probably requires more a higher dimension graph larger than 3D. If you have certain fixed Z values to be substituted in the equation, you can holdZ value constant one at a time to plot multiple 3D plots at different values of Z.