Chapter 10 Review PDF

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Name: ________________________ Chapter 10 Review A professor was curious in figuring out the relationship between number of bites taken and length of Twizzler remaining when students eat one. To do this, she provided each person a single Twizzler and each group a ruler. Prior to taking a bite, she had them measure the length of the Twizzler so they can have the starting length. 1. What is the observational unit in this case? The Twizzlers

2. What is the explanatory variable? Classify as either categorical or quantitative. The number of bites (quantitative)

3. What is the response variable? Classify as either categorical or quantitative. The length of the Twizzler. (quantitative)

4. Was random sampling used? What does this imply? No. We can’t apply it to larger population. We can’t generalize.

5. Was random assignment used? What does this imply? No. There is no randomization with the explanatory variable. We cannot make a cause and effect relationship.

6. Copy and paste the data into the Corr/Regression applet found at www.rossmanchance.com/ISIapplets.html and get the scatterplot. Describe the association between the two variables. (Hint: there are four aspects to think of when describing). Negative, linear, and strong relationship. There are no outliers.

7. Click on the box for the “Correlation Coefficient.” Report this value. r=-0.916 8. Does the correlation coefficient offer support to what you said in problem 6? Explain your answer. Yes, it is close to -1, the closer to -1 the correlation coefficient is, the stronger it is.

9. Using the correlation coefficient, calculate the coefficient of determination. r=-0.916^2 = 83.9%

Name: ________________________

10. Interpret the coefficient of determination in problem 9. 83% of the total variability in the length of the Twizzlers is explained by the linear relationship with the number of bites. 11. Now, select the box next to “Show Regression Line.” Report the equation. Length hat^= 7.64 -1.43 x # of Bites (Explanatory) the hat means it is a predicted value 12. From the regression equation in 11, report the intercept and the slope. Slope= -1.43, the intercept= 7.64 13. Interpret the slope of the line in problem 11 in context. With an increase of every bite, the length of the Twizzler decreases by 1.43 in. on average.

14. Can we interpret the y-intercept from problem 11? If yes, interpret in context. If not, explain why not. Yes, they vary with the average length of every bite. Yes because it is within the range of data and it is meaningful within the context. 15. Considering all validity conditions satisfied test if there is strong negative association between the number of bites and the length of Twizzler. Take α=.05 and the CV for one-sided test is -1.6 or 1.6 and that for two-sided test is ±2. SE for slope is 0.05

1) Ho: B=0 Ha: B...