Kristin's Sleep and GPA Study

So11C & D, Fall 1999 - 31 Completed Surveys; 3 were eliminated because the respondents could not remember their Spring 1999 sleep patterns and did not think that their current patterns were similar to their Spring 1999 patterns.

Here is the on-line survey that most of you filled out over the weekend:

Kristin's Sleep Survey

This survey is anonymous. Please take it only once.

What is your sex?

What is your class?

How old are you?

For last semester (SPRING 1999) what was your semester's GPA?
(If you are a freshmen, then "translate" you high school Spring 1999 grades into a 0 to 4.0 scale.)

During that semester (SPRING 1999) were you engaged in varsity sports?
If so, about how many hours a week did you practice/play that sport?

During that semester (SPRING 1999) were you employed?
If so, about how many hours a week did you work?

How many courses did you take that semester (SPRING 1999)?
Of these, how many would you rate as being very difficult?

During that semester (SPRING 1999) where did you live?

Can you remember your sleep patterns for last semester (SPRING 1999)?
If yes, please answer the following "sleep" questions for last semester (SPRING 1999)
If no, please answer the following "sleep" questions for this semester.

About how many hours of sleep did/do you get on a Monday night?
About how many hours of sleep did/do you get on a Tuesday night?
About how many hours of sleep did/do you get on a Wednesday night?
About how many hours of sleep did/do you get on a Thursday night?
About how many hours of sleep did/do you get on a Friday night?
About how many hours of sleep did/do you get on a Saturday night?
About how many hours of sleep did/do you get on a Sunday night?

If you couldn't remember last semester's sleep patterns, and answered the above questions with respect to this semester, do you think your sleep patterns this semester are substantially the same as last semester?

Thanks for your help .... Press the "Send" Button to submit you answers

Here are some tables and graphs to examine. Remember, our goal is to prove or disprove our hypothesis: the more sleep one gets the higher will be one's GPA.

Frequency Tables (how questions were answered)

Frequency Table

**sex**
.		Frequency	Percent	Valid Percent	Cumulative Percent
Valid	male	7	25.0	25.0	25.0
	female	21	75.0	75.0	100.0
	Total	28	100.0	100.0	.

**class**
.		Frequency	Percent	Valid Percent	Cumulative Percent
Valid	senior	1	3.6	3.6	3.6
	junior	6	21.4	21.4	25.0
	sophomore	19	67.9	67.9	92.9
	freshman	2	7.1	7.1	100.0
	Total	28	100.0	100.0	.

**AGE**
.		Frequency	Percent	Valid Percent	Cumulative Percent
Valid	17	1	3.6	3.6	3.6
	18	3	10.7	10.7	14.3
	19	19	67.9	67.9	82.1
	20	5	17.9	17.9	100.0
	Total	28	100.0	100.0	.

**Play varsity sports during spring 1999?**
.		Frequency	Percent	Valid Percent	Cumulative Percent
Valid	yes	5	17.9	18.5	18.5
	no	22	78.6	81.5	100.0
	Total	27	96.4	100.0	.
Missing	9	1	3.6	.	.
Total		28	100.0	.	.

**Work during spring 1999?**
.		Frequency	Percent	Valid Percent	Cumulative Percent
Valid	yes	14	50.0	50.0	50.0
	no	14	50.0	50.0	100.0
	Total	28	100.0	100.0	.

**number of courses taken, spring 1999**
.		Frequency	Percent	Valid Percent	Cumulative Percent
Valid	4	3	10.7	10.7	10.7
	5	23	82.1	82.1	92.9
	6	2	7.1	7.1	100.0
	Total	28	100.0	100.0	.

**number of very difficult courses**
.		Frequency	Percent	Valid Percent	Cumulative Percent
Valid	0	2	7.1	7.1	7.1
	1	1	3.6	3.6	10.7
	2	8	28.6	28.6	39.3
	3	13	46.4	46.4	85.7
	4	4	14.3	14.3	100.0
	Total	28	100.0	100.0	.

**Where you lived, spring 1999**
.		Frequency	Percent	Valid Percent	Cumulative Percent
Valid	dorm	20	71.4	71.4	71.4
	beach	1	3.6	3.6	75.0
	home	7	25.0	25.0	100.0
	Total	28	100.0	100.0	.

Descriptives

**Descriptive Statistics**
.	N	Minimum	Maximum	Mean	Std. Deviation
AGE	28	17	20	19.00	.67
Spring 1999 GPA	28	1.62000	4.00000	2.9689286	.6724160
weekly hours engaged in sport, spring 1999	5	17.50000	25.00000	20.5000000	2.7386128
weekly hours working, spring 1999	14	4.00000	40.00000	15.6071429	9.7155280
number of courses taken, spring 1999	28	4	6	4.96	.43
number of very difficult courses	28	0	4	2.57	1.03
Hours of sleep on mondays	28	4.00000	8.00000	6.6785714	1.0819588
Hours of sleep on tuesday	28	5.00000	8.00000	6.6785714	1.0293317
Hours of sleep on wednesday	28	3.00000	8.00000	6.6428571	1.2160740
Hours of sleep on thursdays	28	4.00000	10.00000	6.4285714	1.3520512
Hours of sleep on fridays	28	4.00000	10.00000	7.4642857	1.8152062
Hours of sleep on saturdays	28	4.00000	10.00000	7.6964286	1.6960700
Hours of sleep on sundays	28	5.00000	10.00000	6.9642857	1.0708993
Hours of Sleep a Week	28	37.00	60.00	48.5536	5.9866
Hours of Sleep on Week Days	28	25.00	40.00	33.3929	4.0216
Hours of Sleep on Weekends	28	8.00	20.00	15.1607	3.3639
Valid N (listwise)	3	.	.	.	.

In this study testing our basic hypothesis that the amount of sleep affects GPA actually entails looking at two variables from the above descriptives table. Which ones?

"Hours of sleep a week" & "Spring 1999 GPA"

We might also want to examine "Hours of Sleep on Weekdays" & "Spring 1999 GPA"

Is there evidence to support the hypothesis?

Look at the graphs below to "see" if there is a relationship between the amount of sleep and GPA.

Graph

Graph

There is a statistical measure that allows us the "measure" whether two variable are related to each other: the Pearson Correlation Coefficient. This measure has a value for -1 to +1. If two variable are perfectly positively correlated with each other -- that is, if one increases the other one always increases -- then the Pearson Correlation Coefficient will be +1. If two variables are perfectly negatively correlated with each other -- that is, if one decreases the other one always increases -- then the Pearson Correlation Coefficient will be -1. If there is absolutely no relationship between two variables -- that is, if one increases then sometimes the other one increases and an equal number of times it decreases -- then the Pearson Correlation Coefficient will be 0.

Our hypothesis is that Hours of Sleep with be positively correlated with GPA. As the hours of sleep increase, then the GPA will increase. Now let us examine the correlation coefficients for our sleep measures and GPA:

Correlations

**Correlations**
.		Hours of Sleep a Week	Hours of Sleep on Week Days	Hours of Sleep on Weekends	Spring 1999 GPA
Hours of Sleep a Week	Pearson Correlation	1.000	.845(**)	.769(**)	.173
	Sig. (2-tailed)	.	.000	.000	.379
	N	28	28	28	28
Hours of Sleep on Week Days	Pearson Correlation	.845(**)	1.000	.309	.237
	Sig. (2-tailed)	.000	.	.110	.224
	N	28	28	28	28
Hours of Sleep on Weekends	Pearson Correlation	.769(**)	.309	1.000	.024
	Sig. (2-tailed)	.000	.110	.	.902
	N	28	28	28	28
Spring 1999 GPA	Pearson Correlation	.173	.237	.024	1.000
	Sig. (2-tailed)	.379	.224	.902	.
	N	28	28	28	28
** Correlation is significant at the 0.01 level (2-tailed).

These findings suggest a very slight positively correlation between the hours of sleep and GPA -- look at the red, bold, figures. This is not very strong evidence supporting our hypothesis.

Some additional findings:

Means

**Report**
.	Mean			N
	sex			sex
	male	female	Total	male	female	Total
Hours of sleep on mondays	6.7142857	6.6666667	6.6785714	7	21	28
Hours of sleep on tuesday	7.1428571	6.5238095	6.6785714	7	21	28
Hours of sleep on wednesday	7.0000000	6.5238095	6.6428571	7	21	28
Hours of sleep on thursdays	6.7142857	6.3333333	6.4285714	7	21	28
Hours of sleep on fridays	8.4285714	7.1428571	7.4642857	7	21	28
Hours of sleep on saturdays	8.5714286	7.4047619	7.6964286	7	21	28
Hours of sleep on sundays	6.7142857	7.0476190	6.9642857	7	21	28
Hours of Sleep a Week	51.2857	47.6429	48.5536	7	21	28
Hours of Sleep on Week Days	34.2857	33.0952	33.3929	7	21	28
Hours of Sleep on Weekends	17.0000	14.5476	15.1607	7	21	28
Spring 1999 GPA	2.5914286	3.0947619	2.9689286	7	21	28
weekly hours engaged in sport, spring 1999		20.5000000	20.5000000		5	5
weekly hours working, spring 1999	14.0000000	16.2500000	15.6071429	4	10	14

Means

**Report**
.	Mean					N
	class					class
	senior	junior	sophomore	Total	.	senior	junior	sophomore
Hours of sleep on mondays	8.0000000	7.3333333	6.2500000	.	.	1	6	19
Hours of sleep on tuesday	8.0000000	7.1666667	6.2500000	.	.	1	6	19
Hours of sleep on wednesday	8.0000000	6.5000000	6.7500000	.	.	1	6	19
Hours of sleep on thursdays	8.0000000	6.8333333	6.7500000	.	.	1	6	19
Hours of sleep on fridays	8.0000000	8.5000000	7.5000000	.	.	1	6	19
Hours of sleep on saturdays	8.0000000	9.0000000	7.0000000	.	.	1	6	19
Hours of sleep on sundays	8.0000000	7.6666667	7.0000000	.	.	1	6	19
Hours of Sleep a Week	56.0000	53.0000	47.5000	.	.	1	6	19
Hours of Sleep on Week Days	40.0000	35.5000	33.0000	.	.	1	6	19
Hours of Sleep on Weekends	16.0000	17.5000	14.5000	.	.	1	6	19
Spring 1999 GPA	4.0000000	2.8150000	3.4000000	.	.	1	6	19
weekly hours engaged in sport, spring 1999	.	.	17.5000000	.	.	.	.	4
weekly hours working, spring 1999	10.0000000	19.8750000	20.0000000	.	.	1	4	7

Correlations

**Correlations**
.		Spring 1999 GPA	weekly hours engaged in sport, spring 1999	weekly hours working, spring 1999
Spring 1999 GPA	Pearson Correlation	1.000	-.850	-.212
	Sig. (2-tailed)	.	.068	.467
	N	28	5	14
weekly hours engaged in sport, spring 1999	Pearson Correlation	-.850	1.000	-.633
	Sig. (2-tailed)	.068	.	.564
	N	5	5	3
weekly hours working, spring 1999	Pearson Correlation	-.212	-.633	1.000
	Sig. (2-tailed)	.467	.564	.
	N	14	3	14

Look at the strong negative correlation between "weekly hours engaged in sport, spring 1999" & "Spring 1999 GPA." Does this finding make sense? Should someone do a project examining this relationship? Since there were only 5 people who spent time engaged in varsity sports last spring in our sample, this study is not a definitively examination of this topic.