TY - JOUR ID - 72620 TI - Fitting Second-order Models to Mixed Two-level and Four-level Factorial Designs: Is There an Easier Procedure? JO - International Journal of Engineering JA - IJE LA - en SN - 1025-2495 AU - Alqaraghuli, W. A. A. AU - Alkarkhi, A. F. M. AU - Low, H. C. AD - School of Mathematical Sciences, Universiti Sains Malaysia, Penang, Malays AD - School of Industrial Technology, Universiti Sains Malaysia, Penang, Malaysi Y1 - 2015 PY - 2015 VL - 28 IS - 11 SP - 1644 EP - 1650 KW - Two KW - level factorial design KW - four KW - Response Surface Methodology DO - N2 - Fitting response surface models is usually carried out using statistical packages to solve complicated equations in order to produce the estimates of the model coefficients. This paper proposes a new procedure for fitting response surface models to mixed two-level and four-level factorial designs. New and easier formulae are suggested to calculate the linear, quadratic and the interaction coefficients for mixed two-level and four-level factorial designs regardless of the number of factors included in the experiment. The results of the proposed procedure are in agreement with the results of least squares method. This paper could motivate researchers to study the possibility of applying a fixed formula to all factorial designs. UR - https://www.ije.ir/article_72620.html L1 - https://www.ije.ir/article_72620_0e8f7c2944a1b999032e2471e68311ef.pdf ER -