PSY 0371 Week 1 Exam 1

PSY 0371  Week 1 Exam 1 | San Francisco State University | Assignment Help

Final Exam-Question 1-3 (Required)Assignment

Question One (25 points)

For the following set of N=6 numbers:   30    40    50    45    48    49

answer the following:

1.     Compute the mean and the median of these numbers. 

2.     Based solely on the relationship between the mean and the median, would you say that the distribution of scores is symmetrical, negatively skewed, or positively skewed?

3.     List all possible samples of size N=4 that you can obtain from the numbers above.  (HINT: There should be 15 such samples.)

4.     Compute the mean of each sample of size N=4 that you gave for your answer to (3). 

5.     What is the mean of the sample means that you gave for your answer to (4).

-------------------------------------------------------------------------------------------

Question Two (35 points)

For the following set of N=7 numbers:   30  40  50  45  48  49  46

answer the following:

1.     Compute the mean of these numbers. 

2.     Compute the mean deviation of each of the N=7 numbers.

3.     Compute the squared mean deviation of each of the N=7 numbers.

4.     Compute the variance of the original set of scores.

5.     Compute the standard deviation of the original set of scores.

6.     Transform each number in the original set of scores into its corresponding z-score.

7.     What is the mean of the z-scores you obtained in (6)?

8.     What is the standard deviation of the z-scores you obtained in (6)?

---------------------------------------------------------------------------------------------

Question Three (40 points)

In the table below, X = the average number of executive orders made per year for the last six Presidents of the United States, and Y = their approval rating as President:

Answer the following:

1.     Draw a scatterplot for these data.

2.     Calculate the Pearson product-moment correlation coefficient, r.

3.     Is this a positive or a negative correlation?

4.     What proportion of the variance in Y is accounted for by the variance in X?

5.     President Trump has made 51 executive orders.  Use linear regression to predict what his approval rating will be.

6.     Calculate the standard error of estimate for your prediction in (6).

Final Exam-Question 4-5

Submit them directly to Dr. Kim via E-mail: [email protected]

Due: Sunday, December 27

Question Four (10points)

A researcher is interested in whether a new antidepressant drug D has an effect on people's self-rating of depression.  She randomly assigns 12 people into two groups so that each group has 6 people. One group is given drug D daily, and the other group is not given drug D.  Call these the Drug group and the No Drug group, respectively.  After one month of treatment, all 12 people were asked to rate on a scale from 1 to 7 how depressed they felt, where 1 = not depressed at all and 7 = very depressed.  The following are the data:

Using an α-level of .05, perform a two-tailed t-test to determine whether there was an effect of  Drug D on depression ratings.  Specifically, answer the following questions:

1. What is the total degrees of freedom for this problem?
2. Calculate the standard error of the difference between sample means.
3. Calculate the t-score for the difference between sample means, M_D-M_ND
4. Using Table T, what is the critical value of t for this problem?
5. Based on the relationship between the value of t you calculated in (3) and the critical value of t from (4), can the researcher conclude that there is an effect of Drug D on on depression ratings?

--------------------------------------------------------------------------------------

Question Five (10points)

A graduate student realized that the depression study above in Question 4 should have had a placebo condition in which a third group was given a pill just as the people in the Drug condition were, but where the pill was not Drug D (e.g., a sugar pill).  So she designed a new experiment with three conditions -- Drug, No Drug, and Placebo.  To perform the experiment, the graduate student randomly assigned 18 people into the three groups so that each group has 6 people.   After one month of treatment, all 18 people were asked to rate on a scale from 1 to 7 how depressed they felt, where 1 = not depressed at all and 7 = very depressed.  The following are the data:

Using an α-level of .05, perform an Analysis of Variance (ANOVA) to determine whether there is a difference among the three conditions.  Specifically, answer the following questions:

1. What is the within condition degrees of freedom, df_within?
2. What is the within condition sum of squares, SS_within?
3. What is the within condition mean squares, MS_within?
4. What is the between condition degrees of freedom, df_between?
5. What is the between condition sum of squares, SS_between?
6. What is the between condition mean squares, MS_between?
7. Calculate the F-value for this experiment.
8. Using Table F, choose the appropriate critical value of F for this problem.
9. Based on the relationship between the value of F you calculated in (7) and the critical value of F you chose in (8), can the researcher conclude that there is a difference among the three conditions?