Name: ____________________________

Submission Instructions and Due Date: This homework is due a week from when it is assigned, by 11:59 PM - upload via Brightspace as a PDF

Scenario:

You just moved out of your college dorm. The biggest change you've noticed is that you no longer have friends knocking on your door all the time, inviting you to do things that sound more fun than studying. You now study more, and your test scores have improved. You wonder if other people who have recently moved out of the dorms are scoring higher than the mean on their tests. You decide to analyze your social psychology class and choose ten students who recently moved out of the dorms. The mean on the exam of those ten students was a 92 with a standard deviation of 2 and the overall class mean (population) was an 87. Using the steps for hypothesis testing, conduct a one-sample t-test with an alpha level of .05.

• Step 1: What is the alternative hypothesis? Write in proper notation (H₁) (2pts)

• What is the null hypothesis? Write in proper notation (H₀). (2pts)

• Step 2: What is your level? (2pts)

• What are the degrees of freedom for this test? (2pts)

• What is your t-critical value(s)? (Chart at end of homework) (2pts)

• Draw a distribution with your critical region and t-critical value labeled (2pts)

• Step 3: Calculate the one-sample t-test by hand given (remember to find the standard error first): (4pts)

• Step 4: Given the results of the t-test, would you reject the null hypothesis or fail to reject the null hypothesis? What did you find in regard to significance? (2pts)

• Calculate effect size using Cohen's d (2pts)

• Interpret the effect size according to Cohen's guidelines (2pts)

• Which type of error (Type I or Type II) could you have just made? (2pts)

• We have talked about four ways in which we can increase statistical power, which of the following does not increase power? (2pts)
• Increase sample size
• Decrease variability
• Increase alpha level
• Decrease effect size

11. Which term is associated with the probability of making a Type II error: (2pts)

• Alpha
• Beta
• Gamma

12. In a recent research study, I failed to reject the null hypothesis. What type of error could I have made? (2pts.)

Jamovi

At your most recent family gathering there was a large debate about how long the dinner table was. None of your family members could agree on the length so you had to get out the tape measure. The actual length of the table was 55 inches. Below is a table that represents the guesses (in inches) that each of your family members made:

Family Member	Guess for table length
Mom	60
Dad	56
Sister	45
Brother	50
Cousin	57
Aunt	62
Grandma	67

Enter this information into Jamovi and answer the following questions:

• What scale of measurement would length be (nominal, ordinal, continuous)? (1pt)

• Run a one sample t-test in Jamovi and insert your results (be sure to include effect size). (2pt)

• Is this test statistically significant? Would we reject the null hypothesis or fail to reject the null hypothesis? (2pt)

• Include a table of descriptive statistics including the mean, median, mode, SD, and range. (1pt)

• In 1-2 sentences, interpret the results of the t-test. What does this mean? (4pts)