Compute the regression equation and put the line on your scatterplot. Note that the line should "fit" the data much better than the line in question 1. You should get the following picture:

2. What is the regression equation? 3. What is the geometric interpretation of the Least Squares Regression Line? What

does that mean in terms of the graph above question 2 and the graph in question 1?

4. What is the slope of the regression line you computed in question 2? How should

that be interpreted? 5. Does this regression line appear to be a good fit for these data (meaning, is the

relationship between the two variables linear?)? How can you tell? 6. What is the predicted value of y for an observed x-value of 3.5? Now enter a new set of data into your TI-83/TI-84. If you want to use L1 and L2 again, remember to first clear lists 1 and 2. (To clear these lists, either press STAT, 4, 2nd, L1, ,, 2nd, L2, ENTER; or press STAT, 1, move the cursor over the list name in the EDIT screen, and press CLEAR.)

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______________________________ Copyright 2011 Apex Learning Inc. (See Terms of Use at www.apexvs.com/TermsOfUse) TI-83 screens are used with the permission of the publisher. Copyright 1996, Texas Instruments, Incorporated.

Below is a chart of Professor Isaac Asimov's productivity. He was one of the most prolific writers of all time. He wrote more than 500 books during a 40-year career. The data give the time in months required to write his books:

Number of books (x)

Time in months (y)

100 237 200 350 300 419 400 465 500 507

Data Source: Stellan Ohlsson, "The Learning Curve for Writing Books: Evidence from Professor Asimov," Psychological Science 3, no. 6 (1992):380382.

7. What regression equation would you use to predict the time in months required to

write a given number of books? 8. What is the slope of the regression line? Interpret the slope in the context of this

situation. 9. Do these variables appear to be linearly related? Why or why not? Using a chemical procedure called differential pulse polarography, a chemist measured the peak current generated (in microamperes) when a solution containing a given amount of nickel (in parts per billion) is added to a buffer solution.

x = amount of Nickel (parts per billion) y = Peak Current (mA) 19.1 . 095 38.2 . 174 57.3 . 256 76.2 . 348 95 . 429 114 . 500 131 . 580 150 . 651 170 . 722 Data Source: Daniel C. Harris, Quantitative Chemical Analysis, 3rd ed. (New York: W.H. Freeman and Co., 1991).

In your TI-83/TI-84, put x, nickel in parts per billion, in L1 and y, peak current, in L2. 10. What is the equation for the regression line? 11. Use your graphing calculator to draw a scatterplot of the data and the regression line you

identified in question 10. Does the line appear to be a good linear fit?

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______________________________ Copyright 2011 Apex Learning Inc. (See Terms of Use at www.apexvs.com/TermsOfUse) TI-83 screens are used with the permission of the publisher. Copyright 1996, Texas Instruments, Incorporated.

Questions 7, 8, and 9: These questions use data from question 12.7 on page 524 of Introduction to Probability and Statistics, Tenth Edition, by W. Mendenhall, R. Beaver, and B. Beaver. Copyright 1999 by Brooks Cole, division of Thompson Learning Incorporated. Further reproduction is prohibited without permission of the publisher. Questions 10 and 11: These questions use data from question 12.8 on page 524 of Introduction to Probability and Statistics, Tenth Edition, by W. Mendenhall, R. Beaver, and B. Beaver. Copyright 1999 by Brooks Cole, division of Thompson Learning Incorporated. Further reproduction is prohibited without permission of the publisher.

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______________________________ Copyright 2011 Apex Learning Inc. (See Terms of Use at www.apexvs.com/TermsOfUse) TI-83 screens are used with the permission of the publisher. Copyright 1996, Texas Instruments, Incorporated.

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