Analyze Variability

Table of Fitted Means

  

Minitab displays the fitted means for the terms in the model. For a balanced design with no covariates, the fitted mean in the original units for each factor level or combination of factor levels is the same as the average of the standard deviations for that factor or combination.

Example Output

 
 

Means

 

                     Fitted Mean        SE Mean         Fit

Term               (Transformed)  (Transformed)  (Original)

Material

  Formula1                0.8223         0.0680      2.2757

  Formula2               -0.1375         0.0680      0.8716

InjPress

  75                      0.4347         0.0680      1.5444

  150                     0.2502         0.0680      1.2842

InjTemp

  85                      0.3147         0.0680      1.3698

  100                     0.3702         0.0680      1.4480

CoolTemp

  25                      0.4053         0.0680      1.4998

  45                      0.2795         0.0680      1.3224

Material*InjPress

  Formula1 75             0.4186         0.0961      1.5199

  Formula2 75             0.4507         0.0961      1.5694

  Formula1 150            1.2259         0.0961      3.4074

  Formula2 150           -0.7256         0.0961      0.4840

Material*InjTemp

  Formula1 85             0.8883         0.0961      2.4309

  Formula2 85            -0.2589         0.0961      0.7719

  Formula1 100            0.7563         0.0961      2.1304

  Formula2 100           -0.0160         0.0961      0.9841

Interpretation

In this example, the scientists displayed the fitted means for the factors and two interactions. The coefficients table indicates that the interaction between material and injection pressure and the term Material are significant at the 0.05 a-level. You can see that:

·    For the interaction of material by injection pressure, the standard deviation of strength (0.4840) is lower when formula 2 is used and injection pressure is set at 150.

·    For the material, the standard deviation of strength is lower when formula 2 (0.8716) is used than when formula 1 (2.2757) is used.