Hi,
I have used central compoiste design with four variables and 3 levels which gives me 31 experiements. After performing the expeirments, I found that the model is not significant. However, when I used different data (which I prevousluy obtained), I got the good model.
How do I justifiy using user-defined data? and why CCD failed to provide a significant model?
I would be really thankful for your response.