Main Effects

Main effect refers to the primary effect of a factor. A good way to examine the main effects is through a Pareto chart.

The Adams Insight .htm file computes main effects on the fly using JavaScript.

The displayed main effect of a factor is the difference between the response at the factor maximum value and the response at the factor minimum value, while all other factors are at their average values. Effects may be positive (response increases with larger factor value) or negative (response decreases with larger response value).

Note that the minimum and maximum factors' values do not necessarily produce the minimum and maximum response values. If a response is highly nonlinear over the factor value range, the minimum and/or maximum response values may be in the middle of the curve. In this case, the main effects values are meaningless.

The effect % is the ratio of the effect value to the response value with all factors at their average values. An effect % greater than 100% means that the variation in the response value is larger than the average response value.

The effects are sorted largest to least absolute value. The longest bar is always the same length. The other bars are proportional to the largest based on the effect value relative to the largest value. Positive effects have a dark blue bar, negative effects have a light blue bar.