Graziano & Raulin
Research Methods (9th edition)
Testing Hypotheses
with Score Data
Hypotheses with score data are tested with either a t-test or ANOVA. The appropriate test will depend on how many groups there are and on whether the groups are independent or correlated. The appropriate descriptive statistics with score data are the mean, variance, and standard deviation. Those can be computed automatically with SPSS for Windows, but make sure that you request them. If you want more extensive descriptive statistics than available in the inferential statistics module, you can use the descriptive statistics option to compute other statistics, such as the median, mode, and range.
Comparing Two Independent Groups
Independent groups are formed when different people appear in the groups and the groups are selected independently of each other--that is, there is no matching of participants in the groups. If there are two groups, you have the option of using either a t-test or an ANOVA.
Comparing Two Correlated Groups
When the two groups being compared are correlated, the appropriate t-test is the correlated t-test (sometimes called a direct difference t-test) and the appropriate ANOVA is called the repeated-measures ANOVA.
Comparing More than Two Independent Groups
When there are more than two independent groups, the option of a t-test is eliminated and an ANOVA procedure must be used.
| Computing a Mean Manually |
| Computing the Variance and Standard Deviation Manually |
| Computing a One-Way ANOVA Manually |
| Computing Descriptive Statistics with SPSS |
| Computing a One-Way ANOVA with SPSS |
Comparing More than Two Correlated Groups
When there are more than two correlated groups, the option of a t-test is eliminated and a Repeated Measures ANOVA procedure must be used.
Analyzing a Factorial Study
Factorial studies should be analyzed by a factorial ANOVA. Although it is possible to compute a factorial ANOVA manually, it is not generally practical. One of the choices below involves the computation of a simple two-way ANOVA (i.e., both factors are between-subjects factors). However, a quick glance at the complexity of the calculations for this relatively simple ANOVA will convince you that it is best to take the time to learn how to do the computations with a program like SPSS for Windows.
| Computing a Mean Manually |
| Computing the Variance and Standard Deviation Manually |
| Computing a Two-Way ANOVA Manually |
| Computing Descriptive Statistics with SPSS |
| Computing Factorial ANOVAs with SPSS |
Are there any other hypotheses to be tested?
If so, press the RETURN button;
otherwise, press the PROCEED button.