Overview (ONEWAY command)

ONEWAY produces a one-way analysis of variance for an interval-level dependent variable by one independent variable that defines the groups for the analysis. Other procedures that perform an analysis of variance are SUMMARIZE, UNIANOVA, and GLM (GLM is available in SPSS® Statistics Standard Edition or the Advanced Statistics Option). Some tests not included in the other procedures are available as options in ONEWAY.

Options

Trend and contrasts
You can partition the between-groups sums of squares into linear, quadratic, cubic, and higher-order trend components using the POLYNOMIAL subcommand. You can specify up to 10 contrasts to be tested with the t statistic on the CONTRAST subcommand.
Post hoc tests
You can specify 20 different post hoc tests for comparisons of all possible pairs of group means or multiple comparisons using the POSTHOC subcommand.
Statistical display
In addition to the default display, you can obtain means, standard deviations, and other descriptive statistics for each group using the STATISTICS subcommand. Fixed- and random-effects statistics as well as Levene tests for homogeneity of variance are also available.
Matrix input and output
You can write means, standard deviations, and category frequencies to a matrix data file that can be used in subsequent ONEWAY procedures using the MATRIX subcommand. You can also read matrix materials consisting of means, category frequencies, pooled variance, and degrees of freedom for the pooled variance.
Templates
You can specify a template, using the TEMPLATE subcommand, to override the default chart attribute settings on your system.
Criteria
Specifies the options for the procedure. The CILEVEL keyword controls the significance level to estimate the confidence intervals.
Effect size estimation
Controls the effect size estimation. The OVERALL keyword controls the calculation of the effect size for the overall test; the CONTRAST keyword controls the calculation of the effect size for the contrast test.

Basic Specification

The basic specification is a dependent variable, keyword BY, and an independent variable. ONEWAY produces an ANOVA table displaying the between- and within-groups sums of squares, mean squares, degrees of freedom, the F ratio, and the probability of F for each dependent variable by the independent variable.

Subcommand Order

  • The variable list must be specified first.
  • The remaining subcommands can be specified in any order.

Operations

  • All values of the independent variable are used. Each different value creates one category.
  • If a string variable is specified as an independent or dependent variable, ONEWAY is not executed.

Limitations

  • Maximum 100 dependent variables and 1 independent variable.
  • An unlimited number of categories for the independent variable. However, post hoc tests are not performed if the number of nonempty categories exceeds 50. Contrast tests are not performed if the total of empty and nonempty categories exceeds 50.
  • Maximum 1 POLYNOMIAL subcommand.
  • Maximum 1 POSTHOC subcommand.
  • Maximum 10 CONTRAST subcommands.