1. Sampling methods to select independent samples for testing. Please identify some sampling methods to select independent samples for testing.
2. Compute a two-sample independent means t-test
The Dean of the school psychology wants to know which professors' students are scoring higher on statistics final exams. It is believed that Professor A's students are scoring higher on the final exam than Professor B's. To test that hypothesis, the scores for each student are recorded. The results are shown ibelow.
Professor A Student Scores: 42.1, 41.3, 42.4, 43.2, 41.8, 41.0, 41.8, 42.8, 42.3, 42.7
Professor B Student Scores: 42.7, 43.8, 42.5, 43.1, 44.0, 43.6, 43.3, 43.5, 41.7, 44.1
Professor A: Professor B:
Mean: 42.14 Mean: 43.23
Std Dev: 0.683 Std Dev: 0.750
Do the data provide sufficient evidence to conclude that, on the average, Professor A's students perform higher on the final exam? Perform the required hypothesis test at the 5% level of significance.
3. T Tests Discuss the following with the class: Identify the assumptions for a two-independent sample t test. What information can you use to find the critical values in the t table in the back of the course text?
4. Sampling Methods- Describe two sampling methods to select independent groups. (150 words)
5. One-Sample t Test- What are the assumptions of a one-sample t test? What information does the t statistic provide? Why is a t distribution associated with n-1 degrees of freedom?
Question: What information do you need to locate the critical value for a t test?
6. Spearman, point-biserail, and phi coefficient correlation. What are the Spearman, point-biserail, and phi coefficient correlations? When would each be used?
7. Identifying the direction and strength of a linear relationship between variables. Describe the direction and strength of the correlation in the following 4scatterplots. Please explain how you determined your answers.
8. Explain when you would use a Spearman, a point-biserial, and a phi correlation coefficient.
9. Assumptions and Limitations of Correlation Coefficients: Explain three assumptions for the evaluation of a correlation coefficient. Explain three limitations for evaluation a correlation coefficient.
10. Does a negative correlation mean there is a weaker relationship between two variables? Why or why not?