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SPSS® 12.0 Command Syntax Reference

SPSS® 12.0 Command Syntax Reference

SPSS® 12.0 Command Syntax Reference

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1162 ONEWAY<br />

Analysis List<br />

The analysis list consists of a list of dependent variables, keyword BY, and an independent<br />

(grouping) variable.<br />

• Only one analysis list is allowed, and it must be specified before any of the optional<br />

subcommands.<br />

• All variables named must be numeric.<br />

POLYNOMIAL Subcommand<br />

POLYNOMIAL partitions the between-groups sums of squares into linear, quadratic, cubic, or<br />

higher-order trend components. The display is an expanded analysis-of-variance table that<br />

provides the degrees of freedom, sums of squares, mean square, F, and probability of F for<br />

each partition.<br />

• The value specified on POLYNOMIAL indicates the highest-degree polynomial to be used.<br />

• The polynomial value must be a positive integer less than or equal to 5 and less than the<br />

number of groups. If the polynomial specified is greater than the number of groups, the<br />

highest-degree polynomial possible is assumed.<br />

• Only one POLYNOMIAL subcommand can be specified per ONEWAY command. If more<br />

than one is used, only the last one specified is in effect.<br />

• ONEWAY computes the sums of squares for each order polynomial from weighted polynomial<br />

contrasts, using the category of the independent variable as the metric. These<br />

contrasts are orthogonal.<br />

• With unbalanced designs and equal spacing between groups, ONEWAY also computes<br />

sums of squares using the unweighted polynomial contrasts. These contrasts are not<br />

orthogonal.<br />

• The deviation sums of squares are always calculated from the weighted sums of squares<br />

(Speed, 1976).<br />

Example<br />

ONEWAY WELL BY EDUC6<br />

/POLYNOMIAL=2.<br />

• ONEWAY requests an analysis of variance of WELL by EDUC6 with second-order (quadratic)<br />

polynomial contrasts.<br />

• The ANOVA table is expanded to include both linear and quadratic terms.<br />

CONTRAST Subcommand<br />

CONTRAST specifies a priori contrasts to be tested by the t statistic. The specification on<br />

CONTRAST is a vector of coefficients, where each coefficient corresponds to a category of<br />

the independent variable. The Contrast Coefficients table displays the specified contrasts<br />

for each group and the Contrast Tests table displays the value of the contrast and its standard

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