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Comparisons (GLM)Multiple Comparisons |
Use the p-values provided with the hypothesis tests to determine whether pairs of means are different.
Fisher's is less common than Tukey's because it does not control the simultaneous confidence level, which can decrease to an unacceptable level. Instead, Minitab calculates the simultaneous confidence level based on both the individual confidence level that you specify and the number of confidence intervals.
The individual confidence level is the percentage of times that a single confidence interval includes the true difference between factor levels if the study were repeated multiple times.
The simultaneous confidence level is the percentage of times that a group of confidence intervals all include the true differences between factor levels if the study were repeated multiple times.
Example Output |
Fisher Individual Tests for Differences of Means
Difference of Subject Difference SE of Individual 95% Levels of Means Difference CI T-Value P-Value 2 - 1 0.6567 0.0664 ( 0.5215, 0.7918) 9.89 0.000 3 - 1 0.9633 0.0708 ( 0.8192, 1.1074) 13.60 0.000 4 - 1 0.6900 0.0750 ( 0.5375, 0.8425) 9.20 0.000 3 - 2 0.3067 0.0632 ( 0.1782, 0.4352) 4.86 0.000 4 - 2 0.0333 0.0678 (-0.1046, 0.1712) 0.49 0.626 4 - 3 -0.2733 0.0721 (-0.4200, -0.1267) -3.79 0.001
Simultaneous confidence level = 80.38% |
Interpretation |
Pairwise comparisons were conducted for the subject factor of the salary analysis. Because there are four levels of subject, this produces six pairwise comparisons. The hypothesis tests for the comparisons reveal the following:
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