If the dependent variable had been how much participants agreed with a statement, or how helpful they were, or how aggressive they were, you would need to modify the description from "more enjoyable" so that it fit those situations. "more enjoyable" The dependent variable in this study asked participants how enjoyable the task was. You would need to describe each of those comparisons if it were significant. On other problems, you may have 0, 1, 2, or 3 significant comparisons with 3 groups. In the example above, only one comparison was significant. Some will be in degrees Fahrenheit, some will be in dollars, some will be in points on an exam. Not all dependent variables that you use will be on such a scale. The description of the confidence interval includes that it is on a -5 to +5 scale. That is a reasonable approach, but do not copy the template blindly.Ĭonfidence interval units. Students commonly use the block of text above as a template for answering the homework problems involving ANOVA. In the table above, p = 0.210, so no problems: you can use the results that follow. 05, it means that the variances are UNequal, and you should not use the regular old one-way ANOVA. If the value under "Sig." (the p-value) is less than. For the ANOVA to produce an unbiased test, the variances of your groups should be approximately equal. It tests whether the variances in the groups are equal. The above table is similar to the Levene’s test that we saw in the output for the t-test. Next up is a test for the homogeneity of variances: You can see from the above output that the mean for the One Dollar condition is higher ( M = 1.35) than the means for either the Control ( M = -0.45) or the Twenty Dollars condition ( M = -0.05). You should get the following output:įirst, you should get a table of descriptive statistics, reporting the number of observations ( N), means, standard deviations, and 95% Confidence Intervals for the means: Another dialog appears, and you should check the options shown below: "Descriptive" and "Homogeneity of variance test":Ĭlick "Continue" and then "OK". Put it in the "Factor" box.īefore you click "OK", first click the "Options" button on the right side of the dialog (under "Contrasts" and "Post Hoc"). You should now see a new variable available in the One-Way ANOVA dialog: condition2. Put condition in the "Variable → New Name" window, type "condition2" in the "New Name" text box, click the "Add New Name" button, then click "OK". We use the same solution as last time: Transform → Automatic Recode: Know why? The same reason we ran into for t-tests: SPSS demands that all independent variables ("Factors") be numbers. Hmm.looks like we’ve got the dependent variable - enjoyable - but not the independent variable of condition. To test whether the means of the three conditions in Festinger and Carlsmith’s (1959) experiment are unequal, select Analyze → Compare Means → One-Way ANOVA. Whereas a t-test is useful for comparing the means of two levels of an independent variable, one-way ANOVA is useful for comparing the means of two or more levels of an independent variable. Analysis of variance is often abbreviated ANOVA, and one-way ANOVA refers to ANOVA with one independent variable.