This guide contains all of the ASC's statistics resources. If you do not see a topic, suggest it through the suggestion box on the Statistics home page.

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- Statistics Group Sessions

Think of assumptions as prerequisites. These conditions must be met in order for the t-test to be used. Before running the t-test, you would want to test the appropriate assumptions. Most of the t-tests have the same basic assumptions, but there are some slight differences based on the type of t-test being conducted.

- The dependent variable is continuous (interval or ratio).

- review the ASC guide on Levels of Measurement

- attend the What's a Variable group session - Each observation is independent of other observations.

- evaluate the study design - Does any person's score depend on someone else's?

*this important assumption is often not an issue* - No significant outliers.

- Sage Publications resource - The dependent variable should be
*approximately*normally distributed.

- Laerd Statistics guide

- for the Independent Samples T-test: each group should be assessed individually

- for the Dependent Samples T-test: the differences should be assessed for normality

- Independent groups (Independent Samples T-test)

- categorical independent variable with exactly two levels (i.e. yes/no, male/female)

- participants only belong to one group or level of the IV - Paired or related groups (Dependent Samples T-test)

- categorical independent variable with exactly two levels (i.e. pre-test/post-test)

- the same participants provide scores for both groups or levels of the IV - Homogeneity of Variances (Independent and Dependent Samples T-tests)

- are the variances of the two groups approximately the same?

- use Levene's Test by checking the appropriate box in SPSS when running the test

- Last Updated: May 29, 2024 9:48 AM
- URL: https://resources.nu.edu/statsresources
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