Means table for Analyze Variability

Find definitions and interpretation guidance for every statistic in the Means table.

Fitted Mean (transformed)

Fitted natural log of the standard deviation for each factor level or combination of factor levels.

Interpretation

Use the Means table to understand the statistically significant differences between the factor levels. The value of each factor level provides an estimate of the log of each population standard deviation. Look for differences between factor level standard deviations for terms that are statistically significant.

For main effects, the table displays the groups within each factor and their log standard deviations. For interaction effects, the table displays all factor level combinations. If an interaction term is statistically significant, do not interpret the main effects without considering the interaction effects.

In these results, the Means table shows how the strength of insulation varies by material, injection pressure, injection temperature, and cooling temperature. Material is the only factor that is statistically significant at the 0.05 level. However, the interaction between Material and InjPress is also statistically significant at the 0.05 level, so do not interpret the Material main effect without considering the interaction effect.

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.

Means Fitted Mean SE Mean Fit Term (Transformed) (Transformed) (Original) Material Formula1 0.8223 0.0692 2.2757 Formula2 -0.1375 0.0692 0.8716 InjPress 75 0.4347 0.0692 1.5444 150 0.2502 0.0692 1.2842 InjTemp 85 0.3147 0.0692 1.3698 100 0.3702 0.0692 1.4480 CoolTemp 25 0.4053 0.0692 1.4998 45 0.2795 0.0692 1.3224 Material*InjPress Formula1 75 0.4186 0.0979 1.5199 Formula2 75 0.4507 0.0979 1.5694 Formula1 150 1.2259 0.0979 3.4074 Formula2 150 -0.7256 0.0979 0.4840

SE Mean (Transformed)

The standard error of the mean (SE Mean) estimates the variability of the transformed mean between samples that you would obtain if you took samples from the same population again and again. Whereas the standard error of the mean estimates the variability between samples, the standard deviation measures the variability within a single sample.

Interpretation

Use the standard error of the mean to determine how precisely the fitted value estimates the log of the standard deviation.

A smaller value of the standard error of the mean indicates a more precise estimate of the standard deviation. A larger sample size results in a smaller standard error of the mean and a more precise estimate of the standard deviation.

Fit (Original)

The Fit (Original) values are the fitted standard deviation values for each factor level or combination of factor levels.

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