Still regarding this answer:  "It is a mixed-level fractional factorial design. It doesn't really matter what name it has, L18 or otherwise. -- Paige Miller"   Is a L18 or other mixed-level fractional factorial design capable of generate a quadratic model, or just a main effects one? If yes, under which circunstances? ... View more

Thank you for your very helpful informations! ... View more

But we can say that L18 2 x 3^(7–5) design is a L18 fractional factorial design?  ... View more

Paige Miller,   Thanks for your help. The definition that you gave is perfectly in accordance with the characteristics of the L18 Hunter screening Design that I found in the attached article. However, I also found this reference https://www.itl.nist.gov/div898/handbook/pri/section3/pri33a.htm that presents other definition for L18 Designs - 1 factor at two levels and seven factors at 3 levels. I would like to have your opinion on it.   Thank you again, Helena ... View more

Thank you for the suggestion! I already reposted the question in that discussion forum. ... View more