statistics
Week 3 Project – STAT 3001
Student Name: <Type your name here>
Date:<Enter the date on which you began working on this assignment.>
Instructions:To complete this project, you will need the following materials:
- STAT DISK User Manual (found in the classroom in Doc Sharing)
- Access to the Internet to download the STATDISK program.
Part I.Analyze Data
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Instructions |
Answers |
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2-5 Analyze the data in this file and complete the following table, indicating for each variable what type of data it represents. |
Variable |
Qualitative/ Quantitative |
Discrete/ Continuous/ Neither |
Level of Measurement |
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Size |
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Braking (distance) |
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City (MPG) |
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Car |
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6. Would you consider this data to represent a sample or a population? Why? |
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Part II. ScatterPlots
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7. Create a scatterplot for the data in the Length (inches) and Braking distance (feet) columns.Paste it here.You may need to resize the plot once it is in this file. |
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8. Explain the visual relationship between Length and Braking distance. |
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9. Create a scatterplot for the data in Displacement (liters) and Highway (MPG) columns. Paste it here. You may need to resize the plot once it is in this file. |
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10. Explain the visual relationship between Displacement and Highway MPG. |
Part III.Correlation
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11.Using Stat Disk, calculate the linear correlation between the data in the Length and Braking distance columns. List the steps used for the calculation and give the resulting correlation coefficient. |
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12.Explain the mathematical relationship between Length and Braking distance based on the linear correlation coefficient.Be certain to include comments about the magnitude and the direction of the correlation. |
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13.List the sample size and the degrees of freedom for this computation. |
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14.Using Stat Disk, calculate the linear correlation coefficient between the data in the Displacement and Highway MPG columns. |
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15.Compare and contrast these two relationships: Length and Braking distance Displacement and Highway MPG How are they similar? How are they different?
[Hint: Read Page 290 “Types of Correlation”] |
Part IV.Simple Regression
Let’s say that we wanted to be able to predict the city MPG of a car based on its Weight in pounds. Using this sample data, perform a simple-linear regression to determine the line-of-best fit. Use the Weight as your x (independent) variable and City MPG as your y (response) variable. Use 3 places after the decimal in your answer. Refer to page 13 in the Stat Disk User’s Manual.
16. Paste your results here:
Answer the following questions related to this simple regression
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17. What is the equation of the line-of-best fit?Insert the values for bo and b1 from above into y = bo + b1x. |
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18. What is the slope of the line?What does it tell you about the relationship between the Weight and City MPG data? Be sure to specify the proper units. |
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19.What is the y-intercept of the line?What does it tell you about the relationship between Weight and City MPG? |
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20. Using the regression equation, what would you predict for the City MPG of a car weighing 2250 pounds? Show your calculation and round to the nearest tenth. |
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21. Using the regression equation, let’s say you have a car with a City MPG of 29, what would the car weigh? Round to the nearest whole number. |
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22. Find the coefficient of determination (R2 value) for this data.What does this tell you about this relationship? [Hint:see definition on Page 311.] |
Part V.Multiple Regression
Let’s say that we wanted to be able to predict the Highway MPG of a car based on
- Displacement
- Length
- Braking
Using this sample data, perform a multiple-regression using Displacement, Length, Braking distance with Highway MPG as the dependent variable. Refer to page 14 in the Stat Disk User’s Manual.
23. Paste your results here:
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24. What is the equation of the line-of-best fit?The form of the equation is Y = bo + b1X1 + b2X2 + b3X3 (fill in values for b0, b1, b2, and b3). [Round coefficients to 2 decimal places.] |
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25. Using the multiple regression equation, what would you predict for the Highway MPG of a car whose
Round to the nearest tenth. |
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26. What is the R2 value for this regression?What does it tell you about the regression? |
Submit your final draft of your Word file by going to Week 3, Project, and follow the directions under Week 3 Assignment 2.Please use the naming convention “WK3Assgn2+first initial+last name” as the Submission Title.
