Coded experimental variable
= Coded experimental variable
{title2=$x_j=(\xi_j-c_j)/h_j$}
A coded experimental variable rescales a physical setting $\xi_j$ around its center $c_j$, dividing by a chosen positive half-range $h_j$. The endpoints $c_j\pm h_j$ become $\pm1$, giving dimensionless <factorial design> coordinates. The choice of scale affects the metric used for <steepest ascent in response surface methodology>.