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Does time spent on Facebook
affect your grades?
Study results presented by:
Mary Vietti : Power Point Creator
Justin Price : Editor & Conclusion
Jacob Clayton: Lurking & Confounding Variables
Alyssa Schocker : Difficulties & Surprise Encounters
Jessica Brier : Analysis & Conclusion Contributor
All Team Members Contributed to Data Collection
Study question & design
This observational, cross sectional study was constructed to
answer the question of whether time spent on Facebook is
related to a student's grade point average.
•
The study design attempted to gather information that
would be representative of college students in the Salt Lake
City area. The sample includes 115 students. To introduce
randomness, the data was collected from different college
campuses at different times of day. Each student was
asked, "What is your GPA? And then, "How many hours do
you spend on Facebook each week?" Data was also
collected on age and sex of the subject.
Variables Defined
The number of experimental units was determined by the feasibility of
time and access to the students by the study designers.
The explanatory variable is the hours spent on Facebook weekly and
the response variable is GPA. The Facebook variable data will
grouped in classes with a width of 3, so the lowest class limit starts at
3 and ascends by 3 to the last class named 150.
The GPA variable will be grouped into 9 classes. Each spans
25/100th's of a point on a GPA scale that ranges from 1.0 to 4.0. The
lowest class starts with data set 1.76 through 2.0, then ascends with
each following upper class limit as follows; 2.25, 2.5, 2.75, 3.0, 3.25,
3.5, 3.75, and finally 4.0.
EXPLANATORY VARIABLE
The Explanatory variable is “Hours Spent on Facebook Weekly”. The
mean time for the 115 subjects was 8.4 hours per week. The
histogram is skewed to the right. This reflects the fact that more
students spend few hours on Facebook than spend many hours. In
fact, most students spend an hour or fewer a day on Facebook.
Therefor, the median value of 5 is probably a better measure of the
central tendency. The mode of 7 was the most frequent answer
which is the same as 1 hour a day. The standard deviation is quite
large: 15.88 which, as you will see, is related to the outliers in the
data described below.
n=115 subjects, Mean=8.4 hours, Median=5 hours, Mode 7 hours,
standard deviation 15.88 hours
Frequency Histogram
Hours Spent on Facebook Weekly
Box Plot Graph
Time spent on Facebook Weekly
X
X
X
XX
[
--
-------]XX X X
X
I---------I--------I-------I---------I--------I--------I--------I--------I--------I---------I--------I-------I
-15
0
15
120
135
150
165
X
X
30
45
60
75
90
The box plot shows that 50% of the data is between the 2 and 8.5.
The interquartile range is 6.5 around a median value of 5.0.
The lower fence is -7.75 and the upper fence is 18.25.
The outliers include any subject who spent greater than 18.25 hours a week.
The lower fence was -7.75 which is lower than the lowest possible data value of 0.
This leaves 12 outliers which is 10.4% of the data collected.
105
RESPONSE VARIABLE
The response variable is the subject’s “Grade Point
Average, GPA”. The histogram appears skewed to
the left. This reflects the fact that the students
surveyed have good grades. Here, the median value
of 3.5, the mean of 3.46 and the mode of 3.5 are all
probably good measures of the central tendency.
This is supported by the small standard deviation of
.041. All the data is within a small range; see the
box plot graph.
n=115 subjects, Mean GPA=3.46, Median GPA=3.5,
Mode GPA=3.5, standard deviation 0.041
FREQUENCY HISTOGRAM
Grade Point Average
Box Plot Graph
Grade Point Averages
x x
[-------------------------------I--------I--------I---------I
0
2
2.25
-------2.5
2.75
3
]
3.25
3.5
I--------I--------I--------I--------I--------I--------I--------I----3.75
4
4.5
4.75
The box plot shows that 50% of the data is between 3.2 and 3.8.
Therefore the interquartile range is 0.6 around a median value of 3.5.
The lower fence is 2.3 and the upper fence is 4.7.
The outliers include any subject who’s GPA is less than 2.3.
The upper fence is 4.7 which is higher than the highest possible data
value of 4.0.
This leaves 2 outliers which is 1.7% of the data collected.
CORRELATING THE DATA
The data does not have a strong linear correlation. The Linear Correlation
Coefficient was -0.048, which indicates a weak inverse relationship
between the variables. The Line of regression is as follows:
GPA per Facebook Hours
X Axis: Hours Spent On Facebook Per Week
Mean: 8.456 Standard Deviation: 15.876
Y Axis: Grade Point Average
Mean: 3.455 Standard Deviation: 0.415
Line of Regression: Y = -0.0012X + 3.466
Correlation Coefficient: -0.0481 Y intercept: 3.466 Slope: -.0012
Although a line of regression has been applied here to
this data, the linear correlation does not meet the criteria
imposed by a critical value. The 95% Critical Value for a
sample size of 100 or more is 0.195; as listed in the
online textbook, Collaborative Statistics, by B. Illowski,
PH.D. and Susan Dean. This critical value allows only 2
degrees of freedom which is an indication that the data
might have a linear correlation if given looser
parameters.
Difficulties & Surprises
Encounters
Gathering the information for this research assignment was
particularly easy. We surveyed 115 people and asked how
many hours per week they spent on Facebook, and what
their GPA was. StatCrunch made what could have been a
very difficult task, pretty easy. We were able to make all of
the graphs and tables using this program. It was also a
very good review for the things we had learned previously in
the semester. We were surprised that there was no
correlation between Facebook hours and GPA. In fact, one
of the biggest surprises was that some people spent close
to 20 hours on Facebook per week, and they were still able
to maintain a 4.0.
LURKING & CONFOUNDING
VARIABLES
•
•
•
•
How much time a student studies
Difficulty of classes
Number of credit hours
What a student does on Facebook
(they could be doing a group report)
• Overall health of student
• Jobs
• Family Life
Analysis
While the data for GPA appeared to be normally distributed, that
for Facebook hours did not. As we have mentioned, there did
not appear to be a significant linear correlation between the two
variables. Based on Pearson's table, for a sample size of 115,
the absolute value of the correlation coefficient should be
greater than .164 at the 90% level of confidence. The absolute
value of our correlation coefficient is 0.0481, which is less than
.164. Therefore, we do not reject our null hypothesis, which is to
say that there is not a statistically significant relationship
between GPA and Facebook hours per week.
Interpretation and
Conclusions
In conclusion our experiment did not
demonstrate a correlation between GPA and
Facebook use. As we stated in the Lurking and
Confounding Variables there are extenuating
circumstances in student’s lives for them not to
be above the mean. So to answer our question
“Does Time Spent on Facebook Affect Your
GPA”, IT DOES NOT!!!