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Modify formula, standard deviation, group designs, critical

Clarifying the Steps - Chapter 9

9.2. Why do we modify the formula for calculating standard deviation when using t tests (and divide by N - 1)?

9.4. Explain why the standard error for the distribution of sample means is smaller than the standard deviation of sample scores.

9.8. Distinguish between within-group designs and between-group designs.

9.10. How is a t critical value affected by sample size and degrees of freedom?

9.12. Explain what each part of the following statistic means, as it would be reported in the American Psychological Association (APA) format: t(4) = 2.87, p = 0.032.

9.14. When do we use a paired-samples t test?