I'm using a design of experiments method, especially the Box-Behnken matrix. Now comes the time to plot some figures to see the effects of the three constants and I started to do it like in this paper:
http://www.sciencedirect.com/science/article/pii/S016816050700640X
The thing is that when studying 2 of the 3 constants, there are two results for the same point given the constitution of the matrix. Matlab automatically does an average of those two values but I wonder if it's really pertinent as the third value has an effect on the response. So is this method using the average still relevant to analyze the effects?
Can you suggest another method which could be better?
Thanks for your answer Frederik!
Unfortunatly,my problem is more in this type of configuration:
X1 Y1 Z1 R1
X1 Y1 Z2 R2
What i meant is that if i draw the 3D plot according to X, Y and the response R, I'll have a point with same coordinates (X1,Y1) but with two posible responses R1 and R2. So, in that case, Matlab does automatically an average of R1 and R2 (lets call it R12). This new value is then attributed to the point giving the coordinates (X1,Y1,R12).
If you take a look at the literature, papers using design of experiment for 3 variables or more uses 3D plot as i explained earlier whereas this implies that the point (X1,Y1) has a different value from what was found initially. So I wonder, if taking this average as the default Matlab does it, is correct or if acceptable. Does it exits any altenative in Matlab to plot this tipe of figures?
Yes, I check the MATLAB file exchange data base without finding any matches.
Finally, I came up with a solution which I found reading more about DoE. Usually used designs like the one I'm using, Box-Behnken, were constructed based on the association of different blocks. To plot the influence of a particular constant, I only use data contained in the block where the third variable is constant, that way any interaction of the third constant is avoided and so are the double points I spoke about before.
Thanks for your help Frederik!
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