A psychologist has prepared an Optimism Test that is adminis

A psychologist has prepared an “Optimism Test” that is administered yearly to graduating college seniors. The test measures how each graduating class feels about its future – the higher the score, the more optimistic the class. The score ranged from 1 to 20. Last year’s class had a mean score of µ = 15. A sample of n = 50 seniors from this year’s class was selected and tested with a mean score of 11.44 and a standard deviation of 4.68. On the basis of this sample, can the psychologist conclude that this year’s class has a different level of optimism than last year’s class? Set the significant level at = .05. (23 points)

(1) Ho: ___________________________________________________ (1 point)

(2) Ha: ___________________________________________________ (1 point)

(3) Appropriate statistical test (indicate type of statistical procedure, one or two sample, one- or two-tailed, and df if needed). (4 points) ______________________________________________________________________

(4) How much is the test value? (2 point) ______________________________________________________________

(5) What is the probability of this result occurring by chance (in other words, what is the p-value)? (2 point) ______________________________________________________________

(6) What is the critical value/region used to determine whether the null hypothesis is rejected? (2 point) ______________________________________________________________

(7) What is your decision about null hypothesis? (2 points) ______________________________________________________________________

(8) Compute Cohen’s d effect size for this study. (4 points

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