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# Comparing Treatment Means (ANOVA) Help

Treatment means are compared using one of three methods:

The output below is for the example being used in this section with all factors being fixed and for comparing A*B. When comparing components with more than one factor, the program first generates a table of treatment combinations as shown below. Treatment 1 is A at level A1 and B at level B1. Treatment 2 is A at level A1 and B at level B2. The comparisons are then based on these treatments. There is also the option to chart the pairwise comparisons.

### Fisher’s Least Significant Difference Method

The Fisher Least Significant Difference Method is used to compare treatment means. The method compares all pairs of means. It controls the error rate (?) for each individual pairwise comparison but does not control the family error rate. Both error rates are given in the output as shown below.

### Bonferroni’s Method

Bonferroni’s Method is used to compare treatment means.   It controls the family error rate (?).  Both the family error and the individual error rates are given in the output as shown below.

### Tukey’s Method

Tukey’s Method is used to compare means from multiple processes. The method compares all pairs of means. It controls the family error rate (?). Both the family error and the individual error rates are given in the output as shown below.

### Pairwise Charts

The program will chart the confidence interval for each pairwise combination. An example of the A*B combinations using Fisher’s LSD method is shown below.

A zero line is included. Any confidence intervals that do not cross the zero line are considered to have significant differences in the treatment means.

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