How to Perform an Analysis of Variance in SPSS

An analysis of variance (ANOVA) procedure in the statistical program SPSS is used to measure significant differences among more than two means. For example, a researcher may want to test for differences in cholesterol between a group of men and women. A simple t-test may be used. However, the researcher may then want to test the difference between various age groups of the data set which would require an ANOVA as there would be more than two groups of means being tested. The presence of significant F-ratio would indicate difference among the group means.

Instructions

    • 1

      Determine the independent (factor) and dependent variables of the data. These values should be represented numerically in two columns. Using the cholesterol difference among age group example, age would be the independent variable, or factor, with the cholesterol being the dependent variable. The ages must also be represented as groups, such as decades.

    • 2

      Click on the "Analyze" tab, "Compare means" list, and "One-way ANOVA" to bring up a dialog box.

    • 3

      Click the dependent variable column from the list on the right placing it in the "Dependent List" box.

    • 4

      Click the independent variable column from the list on the left placing it in the "Factor" box.

    • 5

      Click on the "Post Hoc" button to distinguish the specific type of procedural test needs to be performed based on whether there are equal or unequal variances (i.e. Tukey or Bonferri test). Consult a statistical reference to determine the specific type of test needed for the particular data set being tested.

    • 6

      Click "Continue," "Options" to bring up the "Options" menu to check which additional output tables will be produced. These include "Descriptives" and "Homogeneity of Variance."

    • 7

      Click "Continue," "OK" to produce the AVOVA results and the previously checked data output tables. The tables will appear in order followed by the ANOVA results table.

    • 8

      Interpret the values to report in the results or to identify additional tests that may be warranted. A guide to interpreting the results of the ANOVA analysis is provided in the Resources section.

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