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Created: Mar 19, 2013
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The Effect of Marijuana on Grade Point Average
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The Effect of Marijuana on Grade Point Average

By: The Purpfectionists

 Grayson Solt, James Steret, Tanner Reel, and Matthew Verheuvel



       We predict that weed will have an effect on your GPA and it will have a moderate negative correlation. We believe that marijuana has certain side effects that will hinder one’s ability to achieve academically. We wanted to study the effects of marijuana on GPA because it is a commonly held belief that smokers are less academically capable. To measure the impact of marijuana on an individual Georgia College student, we added the importance placed on smoking on a scale of one to ten, the amount of marijuana smoked in grams, the number of friends that one preferred to smoke with, the ounces of marijuana bought, and how often they smoke on a scale of one to ten. The total was then compared to GPA to find if there is a correlation between the two. We defined our population as all Georgia College students who smoke marijuana. The variables in our experiment were the number of grams of marijuana smoked in a session by a Georgia College student, the Grade Point Average of a Georgia College student, the number of ounces bought in each transaction by Georgia College students, the importance of smoking marijuana to a Georgia College student on a scale of one to ten, and the number of people that a Georgia College student prefers to smoke marijuana with.



            To obtain the results needed for our experiment, we randomly selected Georgia College students individually. Then, the students who agreed to be surveyed were then asked if they have ever smoked marijuana. If the answer was positive, then we asked them to continue on with our survey. In order to prevent sampling bias we sampled the Georgia College student population in five different locations. These included: the MAX, the library, A & S, the fountain, and the Den. We believed these locations help to prevent sampling bias because it allows us to survey areas with the greatest potential variants in regards to academic ability. Our survey was representative of the population of marijuana smokers who attend Georgia College because the survey was administered at the peak hours of the day in locations where students of all majors and years attended.



Data set 1. Marijuana Project DATA   [Info]
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Result 1: Histogram - Total Scores   [Info]
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Result 7: Simple Linear Regression   [Info]
Simple linear regression results:
Dependent Variable: GPA
Independent Variable: Score 1-30
GPA = 3.5563104 - 0.02126296 Score 1-30
Sample size: 30
R (correlation coefficient) = -0.319
R-sq = 0.10174191
Estimate of error standard deviation: 0.38307995

Parameter estimates:
Parameter Estimate Std. Err. Alternative DF T-Stat P-Value
Intercept 3.5563104 0.17446792 ≠ 0 28 20.383749 <0.0001
Slope -0.02126296 0.011939753 ≠ 0 28 -1.7808543 0.0858

Analysis of variance table for regression model:
Source DF SS MS F-stat P-value
Model 1 0.4654099 0.4654099 3.171442 0.0858
Error 28 4.109007 0.14675024
Total 29 4.5744166

Result 2: Histogram   [Info]
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Result 3: Pie Chart   [Info]
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Result 4: Scatter Plot   [Info]
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Result 5: Pie Chart   [Info]
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Result 6: Pie Chart   [Info]
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 r = -0.319

GPA: 3.556 - (0.021 * score 1-30 )

y(12) = 3.304




            In conclusion to our study, we believe that we found a correlation between GPA and marijuana consumption. We originally stated that we believed that marijuana would have a negative effect on GPA. We found that we have a moderately negative correlation of r=-.32. We found this correlation by comparing the score of each finished survey(1-30) to GPA. The higher the score of a single student, the greater the correlation. The topic of marijuana consumption attracted our group because smoking is a very popular way to socialize in college. Also, its effects can be largely underestimated, or assumed to be an irrelevant issue when brought up in the discussion of GPA.




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By ledler1225
Apr 15, 2013

In your introduction, you listed each question as a variable. Your "marijuana score" should be your explanatory variable and GPA should be the response variable.
The slope is not explained in the report.

Presentation Score 42/50
Report Score 45 /50

Total Score 87 /100
By ledler1225
Mar 20, 2013

Good discussion of introduction with context of problem, population and preliminary predictions.
Included discussion of variables but I think there is some confusion on your explanatory and response variables.
Included discussion of sampling techniques and steps to avoid bias.
Did not include example using prediction line.
Did not discuss slope of the regression equation.
I will post final grades here when ready.

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