Select the options for Comparisons

To perform this analysis in Minitab, go to the menu that you used to fit the model, then choose Comparisons > Options.

Confidence level

Enter a confidence level. The confidence level is the individual confidence level for Fisher's method and the simultaneous confidence level for all other comparison methods. For more information, go to Understanding individual and simultaneous confidence levels in multiple comparisons.

Usually, a confidence level of 95% works well. A 95% confidence level indicates that, if you took 100 random samples from the population, the confidence intervals for approximately 95 of the samples would contain the mean response. For a given set of data, a lower confidence level produces a narrower interval, and a higher confidence level produces a wider interval.

Type of interval

If you chose With a control from Type of comparison in the main dialog box, you can select the type of confidence interval. For the same confidence level, a bound is closer to the point estimate than the two-sided interval. The upper bound does not provide a likely lower value. The lower bound does not provide a likely upper value.

Two-sided: Determine whether the treatment means differ from the control group mean in either direction. An interval is likely to contain the difference between a treatment mean and the control mean.
Lower bound: Determine whether the treatment means are greater than the control group mean. The difference between a treatment mean and the control mean is likely to be greater than the lower bound.
Upper bound: Determine whether the treatment means are less than the control group mean. The difference between a treatment mean and the control mean is likely to be less than the upper bound.