Chapter 9 – Study Notes

 

1. The main focus of Chapter 9 is to form inferences based on sample data that come in ______.
2. What is the first step? What is the second step?
3. _______________ is used to determine whether there is a statistically significant relationship between two variables.
4. _______________ ______________ is used to describe the relationship between two variables with an equation that relates them.
5. What are the assumptions associated with these tests?
6. What is a scatterplot?
7. There are several examples of scatterplots given on page 508, study them until you can identify the type of correlation from the graph.
8. The linear correlation coefficient r measures the _____ of the linear relationship between the paired x and y values in a sample.
9. The example on page 510-1 gives a good illustration of the calculations involved in the Pearson statistic.
10. The value of ‘r’ must always fall between ___ and ___, inclusive.
11. What are the four properties of the linear correlation coefficient?
12. The value of ____ is the proportion of the variation in y that is explained by the linear relationship between x and y.
13. A common source of error involves concluding that correlation implies _______.
14. A ________ variable is one that affects the variables being studied, but is not included in the study.
15. Another source of error arises with data based on _______.
16. Another source of error involves the property of _________.
17. The flowchart on page 515 will help when testing for a linear correlation.
18. The example on pages 515-7 demonstrates both techniques.
19. How can one-tailed tests occur?
20. What is the centroid?
21. The STATDISK procedure is explained on page 519.

 

Do the odd problems on pages 520-5

 

22. The ___________ ______ algebraically describes the relationship between two variables. The graph of this line is called the ___________ ________.
23. This equation models the relationship between the _______________ variable of x and the _________________ variable of y.
24. The slope of the line is _______ and the y-intercept is ______.
25. What are the assumptions that are associated with linear regression.
26. The regression line always passes through the ___________.
27. The regression line fits the sample points best according to the ________ _______ property.
28. What are the rounding rules associated with these calculations?
29. According to the side bar on page 527, is there a relationship between using cell phones and car accidents?
30. Read through the example on page 527.
31. If there is a significant linear correlation, the equation of the regression line can be used for prediction. Otherwise, the best predictor is ___________. The flowchart on page 529 may be helpful.
32. According to the data, the predicted tip for a $100 meal is ______.
33. What are the guidelines for using regression equations?
34. Based on the TIP data, would it be statistically correct to predict a tip based on a $200 meal? Why or why not?
35. What is the marginal change?
36. In a scatterplot, an outlier can have a very dramatic effect on the results. How are outliers identified?
37. The effect of an outlier can be seen in the graph on page 532.
38. What is a residual?
39. A straight line satisfies the ______________  _________________ is the sum of the squares of the residuals is the smallest sum possible.
40. The STATDISK procedure is given on page 534

 

Answer the odd problems on pages 535-538

 

41. Read through the definitions at the top of page 539 and use the figure below the definitions to help to understand the differences between these terms.
42. What is the coefficient of determination?
43. If 68.6% of the total variation in the dependent variable can be explained by the linear relationship, then ______ of the total variation remains unexplained.
44. What is the standard error of estimate?
45. Read through the example on pages 542-544. For a $100 meal, the 95% CI on the tip will be from ________ to ________.
46. The STATDISK procedures are given on page 544.

 

Do the odd problems on pages 545 to 548

 

47. Multiple regression is a method used to analyze relationships involving a dependent variable and _____________ independent variables.
48. What is the difference between the coefficient of determination and the adjusted coefficient of determination?
49. What are the guidelines for using multiple regression?
50. What is stepwise regression?
51. The STATDISK technique is given on page 555

 

Do the odd problems on pages 555 to 558.

 

52. It is unrealistic to assume that all relationships are linear. In fact, most relationships are not. Section 9-6 presents a useful description of some of the tools available to analyze data that is not linear. There are three basic rules on page 559.
53. The population example on pages 560-1 presents a good approach to modeling.
54. The best choice of a model depends upon the set of data being analyzed and requires and exercise in ______, not just computation.

 

Work the odd problems on pages 562-3

 

Do the review exercises and cumulative review exercises on pages 565 –8

 

Students enrolled in Math 1442 should email answers to the following before taking the exam:

• Page 564 – answer the 3 questions in  LETTERS TO THE EDITOR
• Page 570 – answer the questions in the CRITICAL THINKING problem
• Page 568 – in question #1, there are 5 questions, pick one of these. Explain how you would collect unbiased data to analyze this question.

Email the answers to [email protected]

 

The Chapter 9 test will be available starting on __________ until ________. The test consists of 20 multiple choice questions and has a time limit of 40 minutes. You can use your textbook and notes as you take the exam.