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Response surface methodology

Response surface methodology employs experimental design to discover the “shape” of the response surface and then uses geometric concepts to take advantage of the relationships discovered.

Response variable:

The variable that shows the observed results of an experimental treatment. Also known as the output or dependent variable.

Screening experiment:

A technique to discover the most (probable) important factors in an experimental system. Most screening experiments employ two-level designs. A word of caution about the results of screening experiments: if a factor is not highly significant, it does not necessarily mean that it is insignificant.

Robust design:

A term associated with the application of Taguchi experimentation in which a response variable is considered robust or immune to input variables that may be difficult or impossible to control.


Refers to the power to which one or more factors appear in a model.

Sequential experiments:

Experiments are done one after another, not at the same time. This is often required by the type of experimental design being used. Sequential experimentation is the opposite of parallel experimentation.


A geometric figure that has a number ofvertexes (corners) equal to one more than the number of dimensions in the factor space.

Simplex design:

A spatial design used to determine the most desirable variable combination (proportions) in a mixture.

Test coverage:

The percentage of all possible combinations of input factors in an experimental test.


In an experiment, the various factor levels that describe how an experiment is to be carried out. A pH level of 3 and a temperature level of 37° Celsius describe an experimental treatment.