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STAT 1124

Term Project (Sleep & GPA)

Instructions:

• I recommend that you do this project in pairs.

• Project should be typed, with R output pasted to its matching question.

• Please hand in your project in hard copy, at the beginning of class on the due date.

Distribution of Marks

A group of stat students investigated the relationship between sleep (and other variables) to GPA. Data were obtained from a sample of 126 students through a survey. The variables recorded were:

Age (yrs.)

Gender (Male, Female, Other)

Sleep (hrs/day)

GPA (Below Average, Average, Above Average)

Program (Arts, Business, Science)

Commute (One way commute time from home to campus, in minutes)

Study (Time spent on course work in hrs/day)

Nap (Whether regularly take a nap: No, Yes)

Download the data, “Sleep & GPA.csv.” Start R, open the script file “Sleep & GPA.R,” and load the data file. You may need to modify R script from your homework and notes.

1. The students in the survey were asked to rate their current GPA as “Below Average,” “Average,” or “Above Average.” What are the advantage and disadvantage of doing this as opposed to asking student to give their actual GPA (e.g. 2.7, etc.)? [4 marks]

2. How do students generally rate their own GPA? Include the appropriate descriptive statistics (graphs and numbers) and write a brief comment. [4 marks]

3. The survey also asked whether students regularly nap. We want to examine the association between napping and GPA? Produce a contingency table and bar chart to compare percentages of each GPA rating between those who regularly take a nap and those who don’t. Comment on how those who do not nap regularly rate their GPA differently compared to those who do. [4 marks]

4. Is the above comparison statistically significant? Support your answer with the appropriate output(s), and interpret your answer in the context of the problem. [4 marks]

5. What about Programs, do students in different programs have different GPA? Carry out the appropriate test of independence. [3 marks]

6. How much sleep do the students get? Produce the appropriate descriptive statistic (graphs and numbers), and comment briefly. [4 marks]

7. It is generally advised that to maintain good health a person needs 8 hrs per day. What percentage of students in this sample get at least 8 hrs of sleep a day. [1 mark]

8. Is there a relationship between Sleep and GPA? Produce a side-by-side box plot of Sleep hrs. by GPA. And comment briefly. [4 marks]

9. What about between Commute time and GPA, is there a relationship between the two? Produce the appropriate side-by-side box plot, and comment briefly. [4 marks]

10. Is how much a student sleeps related to how much they study? Carry out the appropriate inference. Include the necessary output(s). [4 marks]