Types of quadratic response surface

In practice, the six parameters of a quadratic model are estimated from experimental data. Sometimes the resulting response surface has a well-defined maximum or minimum within the range of factor levels used in the experiment, but the fitted quadratic model may correspond to different shapes.

Examples

The diagram below shows some specific shapes of response surface.

Use the pop-up menu to select different quadratic surfaces and rotate each to help understand the surface shape.

The conclusions from the experiment should depend on the shape of the surface.