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Basic Analysis and Graphing - SAS

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150 Performing Oneway <strong>Analysis</strong> Chapter 5<br />

Compare Means<br />

sample sizes are equal). The comparison circles plot uses the largest quantiles value shown to make the<br />

circles. Use the p-values of the tests to obtain precise assessments of significant differences.<br />

Note the following:<br />

• If a mean has means significantly separated above it, it is not regarded as the maximum.<br />

• If a mean has means significantly separated below it, it is not regarded as the minimum.<br />

• If a mean is significantly separated above all other means, it is regarded as the maximum.<br />

• If a mean is significantly separated below all other means, it is regarded as the minimum.<br />

Note: Means that are not regarded as the maximum or the minimum by MCB are also the means that are<br />

not contained in the selected subset of Gupta (1965) of potential maximums or minimum means.<br />

For the maximum report, a column shows the row mean minus the column mean minus the LSD. If a value<br />

is positive, the row mean is significantly higher than the mean for the column, <strong>and</strong> the mean for the column<br />

is not the maximum.<br />

For the minimum report, a column shows the row mean minus the column mean plus the LSD. If a value is<br />

negative, the row mean is significantly less than the mean for the column, <strong>and</strong> the mean for the column is<br />

not the minimum.<br />

Related Information<br />

• “Example of the With Best, Hsu MCB Test” on page 167<br />

With Control, Dunnett’s<br />

The With Control, Dunnett’s test compares a set of means against the mean of a control group. The LSDs<br />

that it produces are between the Student’s t <strong>and</strong> Tukey-Kramer LSDs, because they are sized to guard against<br />

an intermediate number of comparisons.<br />

In the Dunnett’s report, the d quantile appears, <strong>and</strong> can be used in a manner similar to a Student’s<br />

t-statistic. The LSD threshold matrix shows the absolute value of the difference minus the LSD. If a value is<br />

positive, its mean is more than the LSD apart from the control group mean <strong>and</strong> is therefore significantly<br />

different.<br />

Related Information<br />

• “Example of the With Control, Dunnett’s Test” on page 168<br />

Compare Means Options<br />

The Means Comparisons reports for all four tests contain a red triangle menu with customization options.

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