Analyze Factorial Design

Two-Level Split-Plot Designs
Estimated Effects and Coefficients Table - Effects

  

Look at the Effect to determine the relative strength of the effects.

·    The absolute value of the effect determines its relative strength. The higher the value, the greater the effect on the response.

·    The sign of the effect determines which factor setting results in a higher response measurement.

-    For main effects, a positive sign indicates that the high factor setting results in a higher response than the low setting.

-    For main effects, a negative sign indicates that the low factor setting results in a higher response than the high setting.

Example Output

Coded Coefficients

 

Term                     Effect    Coef  SE Coef  T-Value  P-Value   VIF

Constant                         50.875    0.811    62.70    0.000

Pretreatment[HTC]        -8.050  -4.025    0.811    -4.96    0.008     *

Stain                    -0.050  -0.025    0.739    -0.03    0.975  1.00

Pretreatment[HTC]*Stain   4.483   2.242    0.739     3.03    0.039  1.00

Interpretation

For the water resistance data, the effects suggest the following:

·    Pretreatment has the greatest effect (-8.050) on water resistance. The negative sign indicates that Pretreatment A results in a higher water resistance than Pretreatment B.

·    Pretreatment*Stain has the second greatest effect (4.483) on water resistance.

·    Stain has the smallest effect (-0.050) on water resistance. The negative sign indicates that Stain A results in a higher water resistance than Stain B.