STAT Help!

Name: ____________________________________.

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. A researcher discovers that if people eat a certain fruit before a test, the more fruit eaten, the better they do on the test. Beyond a certain point, however, the more fruit eaten the worse people do on the test. The relation between the amount of fruit eaten and how well people do on the test is an example of:

a) a positive linear correlation

b) a curvilinear correlation

c) a negative linear correlation

d) no correlation

2. Mirvis and Lawler (1977) found that the higher the level of job satisfaction, the lower the level of absenteeism. Research on this topic has continued to show this __________ pattern all over the world and for university classes.

a) positive linear correlational

b) positive curvilinear correlational

c) negative curvilinear correlational

d) negative linear correlational

3. The example showing a positive relationship between response time and accuracy tells us that:

(Note: longer response time means slower responses)

a) the slowest responders are always the most accurate.

b) the fastest responders are always the most accurate.

c) slower responders are more accurate than faster responders.

d) speed is a virtue.

4. You are interested in the relation between the number of years working for a particular company and loneliness at work. You surveyed 40 workers at this company and found a correlation between these two variables of .90. This is considered a:

a) weak positive linear correlation

b) weak negative linear correlation

c) strong positive linear correlation

d) strong negative linear correlation

5. You conducted a study in which you measured two political attitudes and found a correlation of +.03. This is considered a:

a) weak positive linear correlation

b) weak negative linear correlation

c) moderate positive linear correlation

d) moderate negative linear correlation

6. Two variables, X and Y, have a strong linear correlation. Under what conditions can you determine the direction of causality just from knowing the correlation coefficient?

a) When the correlation is negative

b) When the correlation is positive

c) When the magnitude of the correlation is large

d) None of the above

7. Which of the following represents the strongest linear correlation?

a) +.09

b) +.88

c) −.92

d) −.18

8. The correlation between the amount of caffeine consumed and nervous behavior was found to be .30. What conclusion can be drawn from this finding?

a) 30% of the variability in nervous behavior can be explained by the amount of caffeine consumed

b) 9% of the variability in nervous behavior can be explained by the amount of caffeine consumed

c) The correlation between nervous behavior and caffeine consumption is not significant

d) Consuming caffeine causes nervousness

9. Compare these two correlation coefficients: r1 = .3 and r2 = .9

a) r2 is three times as strong as r1

b) r2 is nine times as strong as r1

c) r1 is three times as strong as r2

d) these correlation coefficients are equally strong

10. General State University recently decided to discontinue its use of the GRE as an admissions tool for its graduate programs because they observed no correlation between GRE scores and subsequent GPAs. Ninety percent of the grades awarded in the graduate programs at General State University are A’s. What General State has failed to consider in this situation is the issue of _________________________. a) curvilinear relationships.

b) causality.

c) the third variable problem.

d) restrictive range.

11. The three scatterplots below are showing the cases or r = 0. Using these cases, explain why it is important to examine a scatterplot of the data in addition to calculating a correlation coefficient.

(a) (b) (c)

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12. What is the third variable problem and how does the partial correlation technique help with this problem?

______________________________________________________________________________

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13. A recent study found that the correlation between self-esteem and Facebook-hours was .64.

(a) Explain what this means.

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

(b) Calculate the coefficient of determination for this correlation and explain what information this provides.

______________________________________________________________________________

______________________________________________________________________________

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(c) Tom interprets this correlation to mean that people with low self-esteem tend to use Facebook longer. What is the problem with Tom’s interpretation? ______________________________________________________________________________

______________________________________________________________________________

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14. A researcher studied the relationship between familiarity of certain unusual words and the time participant took to indicate whether the word is singular or plural. Participants rated their familiarity of the words (at the end of the experiment) on a 7-point scale (the higher the score, the more familiar with the word). Below are the scores of four participants.

Person A: familiarity score = 6, reaction time = 1

Person B: familiarity score = 2, reaction time = 3

Person C: familiarity score = 3, reaction time = 2

Person D: familiarity score = 1, reaction time = 6

What’s the correlation between the two variables (Familiarity and Reaction Time)?

(Use three decimal places during your calculations and for your answer) Show your work.

SPSS Practice 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).

1. One of my favorite activities, especially when trying to do brain-melting things like studying statistics, is drinking tea. Fortunately, tea improves your cognitive function, well, in old Chinese people at any rate (Feng, Gwee, Kua, & Ng, 2010). I may not be Chinese and I’m not that old, but I nevertheless enjoy the idea that tea might help me think. Here’s some data based on Feng et al.’s study that measured the number of cups of tea drunk per day and cognitive functioning in 15 people. Enter the data in SPSS and:

a) Draw the scatterplot.

b) What is the correlation between tea drinking and cognitive functioning? _______

c) How much of the variance of the cognitive function can be explained by tea taking per day (i.e., what is the coefficient of determination)? ________

d) Verbally describe 3 possible directions of the relationship.

1._________________________________________________________________________

2._________________________________________________________________________

3._________________________________________________________________________

e) Predict the score of the cognitive function of a person who has six cups of tea per day. [This question e) is not an SPSS work. Show your manual calculation work below]

f) Extra credit work: Show the r-calculating table with raw scores and labels. No need to fill in the cells.