STAT Help!

Name: ____________________________________.

Instructions

1. Show all of your work on this assignment. If you provide answers without showing your work or explanation, then you will lose all the points associated with the questions.

2. Clearly and legibly PRINT your answer.

3. Use three decimal places in your calculation and answer (unless noted otherwise).

1. Create two small sets of scores (N = 5) with equal ranges , but different standard deviations .

Your 1st set of scores: ___, ___, ___, ___, and ___.

Your 2nd set of scores: ___, ___, ___, ___, and ___.

Show your work for the mean, variance, and standard deviation.

2. Using the six digits of your student ID number after the first four zeros, create a variable X with six scores. For example, if your student id is 0000114392, then your variable X has the following six scores: 1, 1, 4, 3, 9, and 2. Calculate the mean, variance, and standard deviation manually. Show your work:

3. Students who read the textbook prior to taking an exam have a mean of 9 (s = 1). Students who do not read the textbook have a mean of 6 (s = 2). It suggests that ( circle one of the words in the parentheses below to indicate the answer):

(1) In general, students who read the textbook receive (lower / higher) scores than the students who don’t read the textbook.

(2) Students who read the textbook show (less / more) individual differences with respect to the obtained scores than the students who don’t read the textbook.

4. Draw two distributions with the same standard deviations but different means (draw them in the same plane). Assuming that the two distributions represent the study hours of two groups of people (e.g., male vs. female) before exam, verbally describe what the same standard deviation and different mean suggest.

5. Draw two distributions with the same mean but with different standard deviations (draw them in the same plane). Assuming that the two distributions represent average sleep hours of the two groups of people (e.g., male vs. female), verbally explain what the same mean and different standard deviations indicate.

6. A certain score’s z score is 2. The distribution from which the specific score came has a mean of 80 and a standard deviation of 10. What is the raw score ? Show your work.

7. After attending a communication skill seminar for couples, a girlfriend obtained a communication skill score of 75, while her boyfriend scored 70. Overall, women’s average communication skill score after the seminar is 70 (s = 10) while men’s average score after the seminar is 65 (s = 5). Relative to others of their own gender , who has a better communication skill score after the seminar? Show your work.

8. Lee took a statistics class last year but failed. Here’s the score he earned from the class (Class 1) along with the class’s mean and standard deviation.

Lee’s score in Class 1 = 55.

Class 1’s mean and standard deviation: = 70, s = 10.

He took the course again from a different instructor, and here’s his score from the second class (Class 2).

Lee’s score in Class 2 = 45.

Class 2’s mean and standard deviation: = 35, s = 5.

Compute Lee’s z scores for Class 1 and 2, and discuss his performances in the two classes in relation to the other people in each class .

9. Psychology students at KSU buy an average of 5 cups of coffee per month from the Starbucks at the social science building with a standard deviation of 1.5. The distribution is normal. Do the default sketching regarding this variable. That is, sketch the distribution of the variable with the following markers :

a) Raw mean score and its corresponding z score .

b) Two vertical bars under the distribution indicating one standard deviation above and below the mean. Mark their corresponding raw scores, z scores, and proportions of scores between the mean and the bars’ points under the normal curve.

c) Two vertical bars indicating two standard deviations above and below the mean. Mark their corresponding raw scores, z scores, and proportions of scores between the mean and the bars’ points under the normal curve.

(show the answer for question a, b, and c in the below plane)

Raw Scores

Z Scores

d) Mark two zcritical scores that leaves 5% of scores beyond them (i.e., 2.5% on each end). Mark their corresponding raw scores as well. Show your work.

e) Mark two zcritical that leaves 10% of scores beyond them (i.e., 5% on each end). Mark their corresponding raw scores as well. Show your work.

(show the answer for question d and e in the below plane)

Raw Scores

Z Scores

For each of the following questions, sketch the distribution and shade the area of interests . Also, mark the relevant raw and z scores on the X-axis. Show your work.

f) How many cups of coffee would 90% of the typical psychology students buy per month from the Starbucks (the shaded area should be centered around the mean of the distribution)?

Raw Scores

Z Scores

g) How many cups of coffee would 95% of the typical psychology students buy per month from the Starbucks (the shaded area should be centered around the mean of the distribution)?

Raw Scores

Z Scores

Let’s say you buy 8 cups of coffee per month from the Starbucks.

h) What is your z score? Show your work.

i) What is your percentile rank?

j) What percent of students would buy more coffee than you do?

k) Let’s say the z score of the number of cans you purchase per month from a vending machine is -1 in comparison to other psychology students. Discuss the number of drinks you buy from a vending machine and Starbucks in comparison to other psychology students.

SPSS Practice Tasks

General instructions for the SPSS tasks

· As an outcome of the SPSS Practice Tasks, you need to generate two kinds of SPSS files: SPSS data editor file (.sav) and SPSS output viewer file (.spv). Post them in the assignment folder, [Manual Calculation and SPSS Practice #].

· You need to post a .sav file that includes ALL the raw data needed for the SPSS Practice tasks.

· Do not post multiple .sav files. Instead, keep all the raw data used in a single .sav file (i.e., use different columns for different variables).

· Remember to give an appropriate name to the variable. No variable name would cause a point deduction for each question.

· Similarly, you need to post a single .spv file that includes all the outputs (SPSS will add results to the previous results and will give you just one output file unless you close the output file from the previous analysis).

Do not post multiple .spv files. Also, in the posted .spv file, keep proper outcomes only and eliminate other outcomes that were generated while you were working on this homework (to delete an item in the output file, select the item – right click – hit cut).

10. Create two small sets of scores (N = 5) with equal ranges , but different standard deviations .

Your 1st set of scores: ___, ___, ___, ___, and ___. Standard deviation (s): __________.

Your 2nd set of scores: ___, ___, ___, ___, and ___. Standard deviation (s): __________.

Calculate the range, mean, and standard deviation using SPSS.

11. Using the six digits of your student ID number after the first four zeros, create a variable X with six scores. For example, if your student id is 0000114392, then your variable X has the following six scores: 1, 1, 4, 3, 9, and 2.

Report the mean and standard deviation of the six scores using SPSS. Also, report the z score and percentile ranks of these six scores using SPSS.

12. Celebrities always seem to be getting divorced. The (approximate) length of some celebrity marriages in days are: 240 (J-Lo and Cris Judd), 144 (Charlie Sheen and Donna Peele), 143 (Pamela Anderson and Kid Rock), 72 (Kim Kardashian, if you can call her a celebrity), 30 (Drew Barrymore and Jeremy Thomas), 26 (Axl Rose and Erin Everly), 2 (Britney Spears and Jason Alexander), 150 (Drew Barrymore again, but this time with Tom Green), 14 (Eddie Murphy and Tracy Edmonds), 150 (Renee Zellweger and Kenny Chesney), 1657 (Jennifer Aniston and Brad Pitt).

Again, the scores are 240, 144, 143, 72, 30, 26, 2, 150, 14, 150, 1657

Calculate the mean, median, mode, variance, and standard deviation. (You just need to post the SPSS work for these values)

Mean:

Median:

Mode:

Variance:

Standard deviation:

13. Repeat the above task but excluding Jennifer Anniston and Brad Pitt’s marriage. That is, calculate the following measures.

(You just need to post the SPSS work for these values)

Mean:

Median:

Mode:

Variance:

Standard deviation:

Discuss how an unusual score (outlier) affects the five measures by comparing the values from the above the two tasks (with and without Jenn and Brad). Write down the answer over here.

-The End-