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Basic Analysis and Graphing - SAS

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Chapter 5 Performing Oneway <strong>Analysis</strong> 147<br />

Compare Means<br />

Option Description Reference Nonparametric<br />

Menu Option<br />

Each Pair,<br />

Student’s t<br />

Computes individual pairwise<br />

comparisons using Student’s<br />

t-tests. If you make many<br />

pairwise tests, there is no<br />

protection across the inferences.<br />

Therefore, the alpha-size (Type I<br />

error rate) across the hypothesis<br />

tests is higher than that for<br />

individual tests.<br />

See “Each Pair,<br />

Student’s t” on<br />

page 149.<br />

Nonparametric ><br />

Nonparametric<br />

Multiple<br />

Comparisons ><br />

Wilcoxon Each<br />

Pair<br />

All Pairs, Tukey<br />

HSD<br />

Shows a test that is sized for all<br />

differences among the means.<br />

This is the Tukey or<br />

Tukey-Kramer HSD (honestly<br />

significant difference) test.<br />

(Tukey 1953, Kramer 1956).<br />

This test is an exact alpha-level<br />

test if the sample sizes are the<br />

same, <strong>and</strong> conservative if the<br />

sample sizes are different<br />

(Hayter 1984).<br />

See “All Pairs, Tukey<br />

HSD” on page 149.<br />

Nonparametric ><br />

Nonparametric<br />

Multiple<br />

Comparisons ><br />

Steel-Dwass All<br />

Pairs<br />

With Best, Hsu<br />

MCB<br />

Tests whether the means are less<br />

than the unknown maximum or<br />

greater than the unknown<br />

minimum. This is the Hsu<br />

MCB test (Hsu 1981).<br />

See “With Best, Hsu<br />

MCB” on page 149.<br />

none<br />

With Control,<br />

Dunnett’s<br />

Tests whether the means are<br />

different from the mean of a<br />

control group. This is Dunnett’s<br />

test (Dunnett 1955).<br />

See “With Control,<br />

Dunnett’s” on<br />

page 150.<br />

Nonparametric ><br />

Nonparametric<br />

Multiple<br />

Comparisons ><br />

Steel With Control<br />

Note: If you have specified a Block column, then the multiple comparison methods are performed on data<br />

that has been adjusted for the Block means.<br />

Related Information<br />

• “Example Contrasting All of the Compare Means Tests” on page 169

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