Coded units (−1 / +1)

factor settings written as low and high

x_coded = (x − centre) / (half range)

In a 2-level design the low setting is written as −1 and the high setting as +1. Coding puts all factors on the same scale, so the coefficients of the model can be compared directly, and makes the columns of the design orthogonal.

A coefficient in coded units is half the effect, because the factor moves two units from −1 to +1.

Calculate it

DOE: 2-Level Factorial Design: 2^k factorial: run plan, effects, Pareto, interaction plots and best settings.

Related terms

• Factor and level: what is changed and to which settings
• Main effect: average change when one factor goes from low to high