Centre points

runs with every factor at its middle setting

Extra runs at the midpoint between the low and high levels of every numeric factor. They check whether the response is curved between the corners of the design and add degrees of freedom for the pure error without repeating the whole design.

Significant curvature means a 2-level model is not enough and a response surface design is the next step.

Calculate it

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

Related terms

• Factorial design (2^k): every combination of the factor levels
• Pure error: noise estimated from replicated runs