Hi, I am trying to do a screening of mixture with 12 components using extreme vertices mixture design. I have the specific range to test:
X1: 0.541 to 0.784
X2: 0 to 0.147
X3: 0 to 0.08
For X4 to X 12, I am testing them using the same range between 0.216-0.324 to find which of them are suitable for my formulations. However, when I tried to key in the lower limit, only 2 components are possible. From X6 onwards, it did not allow me to set the lower limit at 0.216, but reset to 0 instead. I do not understand why is it so? I have no problem in setting the upper limit for all.
Hence, I tried to set the linear constraint as follow:
I am not certain if my linear constraint is correct
I generated a subset table with 25 trials and realize that most runs will have 0 value in the multiple components. Also component X3 is only tested either 0 or 0.08. I felt that something is not quite right. Is there any advice for me to improve the design?
Thanks in advance!
Glenna
