Lecture 14: Related- Samples t Test 2011, 11, 3

Lecture Topics When to use related-samples t-test? What is mean difference (D)? Five steps for related-samples t-test.**

Are You Satisfied with Your Romantic Relationship? Do girls tend to be less satisfied with their romantic relationships than boys? You surveyed 10 pairs on campus with the Relationship Satisfaction Scale with 1 = Least Satisfied and 5 = Most Satisfied. Here is your data: Step 1: State you hypothesis: GirlsBoysDiff

= Averaged pair- difference for each sample n = 10 Hypothesized Population  D =0 Probability Means Your Sample:

Example 1: Do girls tend to be less satisfied with their romantic relationships than boys? Step 1: State hypotheses Step 2: State criteria One-tailed test df = 10 – 1 = 9 t crit = Step 3: Compute the estimated standard error p=.05

Step 4: Compute the t obs score Step 5: Compare t crit to t obs, and state the conclusion We reject the null. Girls are significantly less satisfied with their romantic relations than boys. Example 1: Do girls tend to be less satisfied with their romantic relationships than boys? p=.05

Related-Samples t Test a.k.a. Paired-Samples; Matched-Samples Condition: When we have paired data (e.g., data collected from couples), we use related- samples t test to examine if there is any difference between husband and wife. The paired data could also be pretest score and post test score Solution: Examining the difference score

Lecture Recap: Related-Sample t-Test When to use related-sample t-test? Five steps to conduct a related-sample t-test. The distribution for mean differences ( ). Mean  Std. Err.  How to compute the t obs