Code Actual value of factor
- α Xmin
-1 (α-1)xmax+(α+1)xmin/2α
0 xmax+ xmin/2
+1 (α-1)xmin+(α+1)xmax/2α
Xmax
Xmax and Xmin : maximum and minimum value of  X
Table 2: Relationship between the coded and actual values of a factor.