Chapter 12 Correlation Concepts (counts towards your grade)

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12/14/23, 5:00 PM Chapter 12 Correlation Concepts (counts towards your grade) https://egcc.instructure.com/courses/40375/assignments/1211295?module_item_id=3857986 1/9 Question 1 1/1 pt Details Question 2 1/1 pt Details Question 3 1/1 pt Details Question 4 1/1 pt Details Which correlation coefficient does not belong with the other three? Question Help: Video Message instructor Interpret the Correlation Coefficient 0.14 It is Strong Negative It is Strong Positive It is Weak Positive It is Weak Negative Question Help: Video Message instructor The correlation coefficient, , is a number between 0 and 1 -10 and 10 -1 and 1 and 0 and 0 and 10 0 and 100 Question Help: Message instructor Which of the following is false ?

12/14/23, 5:00 PM Chapter 12 Correlation Concepts (counts towards your grade) https://egcc.instructure.com/courses/40375/assignments/1211295?module_item_id=3857986 2/9 Question 5 1/1 pt Details Question 6 1/1 pt Details Question 7 1/1 pt Details Correlation measures the strength of linear association between two numerical variables. If the correlation between two variables is close to 0.01, then there is a very weak linear relation between them. Correlation coefficient and the slope always have the same sign (positive or negative). If the correlation coefficient is 1, then the slope must be 1 as well. Question Help: Message instructor Which of the following pairs of variables is likely to have a negative correlation? Check all that apply. The square footage of a home and its price Years of education and salary A person's height and their favorite color The speed of a car and the time to its destination The number of miles run and the number of calories burned Question Help: Video Message instructor True or False: Correlation implies causation False True Question Help: Message instructor Match each scatterplot shown below with the best desciption of its correlation.

12/14/23, 5:00 PM Chapter 12 Correlation Concepts (counts towards your grade) https://egcc.instructure.com/courses/40375/assignments/1211295?module_item_id=3857986 3/9 Question 8 1/1 pt Details Question Help: Negative correlation No correlation Positive Correlation Video Message instructor a. 0.86 b. -0.26 c. 0.32 d. -0.96 Match each scatterplot shown below with one of the four specified correlations. c

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12/14/23, 5:00 PM Chapter 12 Correlation Concepts (counts towards your grade) https://egcc.instructure.com/courses/40375/assignments/1211295?module_item_id=3857986 4/9 Question 9 1/1 pt Details Question Help: b a d Video Message instructor a. 0.95 b. -0.94 c. -0.18 d. 0.12 Match each scatterplot shown below with one of the four specified correlations. a

12/14/23, 5:00 PM Chapter 12 Correlation Concepts (counts towards your grade) https://egcc.instructure.com/courses/40375/assignments/1211295?module_item_id=3857986 5/9 Question 10 1/1 pt Details Question Help: d b c Message instructor The scatterplots below show the relationship between height, diameter, and volume of timber in 31 felled black cherry trees. The diameter of the tree is measured 4.5 feet above the ground.

12/14/23, 5:00 PM Chapter 12 Correlation Concepts (counts towards your grade) https://egcc.instructure.com/courses/40375/assignments/1211295?module_item_id=3857986 6/9 a) Describe the relationship between height and volume of these trees. strong, positive weak/moderate, positive b) Describe the relationship between diameter and volume of these trees. weak/moderate, positive strong, positive c) Suppose you have height and diameter measurements for another black cherry tree. Which of these variables would be preferable to use to predict the volume of timber in this tree using a linear regression model? diameter height Hint: Help

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12/14/23, 5:00 PM Chapter 12 Correlation Concepts (counts towards your grade) https://egcc.instructure.com/courses/40375/assignments/1211295?module_item_id=3857986 7/9 Question 11 1/1 pt Details Question 12 1/1 pt Details Question Help: Message instructor True False True False True False The scatter plot shows the relationship between the number of minutes studying for a test ( x ) and the number of mistakes made ( y ). The graph shows the scatterplot of the data and a fitted line. 10 20 30 40 50 60 70 80 90 100 110 120 -10 1 2 3 4 5 6 7 8 9 10 11 12 -1 -2 -3 Select True or False for each statement based on the scatter plot. True/False There is a negative association between the amount of time studying for a test and the number of mistakes made. Students who studied for a longer period of time tended to make more mistakes. There is a linear association between time studying and number of mistakes. Question Help: Message instructor Annual high temperatures in a certain location have been tracked for several years. Let represent the year and the high temperature. Based on the data shown below, calculate the correlation coefficient (to three decimal places) between and . Use your calculator! x y 3 10.64 4 14.92 5 16.6 6 18.18 7 22.76 8 23.44 9 29.62 10 30.5 11 32.08 12 34.56

12/14/23, 5:00 PM Chapter 12 Correlation Concepts (counts towards your grade) https://egcc.instructure.com/courses/40375/assignments/1211295?module_item_id=3857986 8/9 Question 13 1/1 pt Details Question 14 1/1 pt Details x y 13 38.34 14 42.22 15 42.4 .995 Question Help: Message instructor Rivers in North Carolina contain small concentrations of mercury that can accumulate in fish over their lifetimes. The concentration of mercury in fish tissue can be obtained by catching fish and sending samples to a lab for analysis. A study was conducted on fish from the Waccamaw and Lumber Rivers to investigate mercury levels in tissues of largemouth bass. At several stations along each river a group of fish were caught, weighed and measured; in addition a filet from each fish was sent to a lab so that the tissue concentration of mercury could be determined. In all, 171 fish were caught at 15 different research stations along the Waccamaw and Lumber Rivers. Data from fish caught at one of these stations is shown in the following table: length weight 1616 47.0 1862 48.7 2855 55.7 1199 45.2 1320 44.7 1225 43.8 870 38.5 1455 45.8 1220 44.0 1033 40.4 Compute the correlation between length and weight for these fish. (Assume the correlation conditions have been satisfied and round your answer to the nearest 0.001.) .968 Question Help: Video Message instructor Recently a community college offered a 2-credit course to help students with math anxiety. At the beginning of the course, each student took a 30-question survey (called MARS-S); the higher the score, the more anxiety experienced by the student. The nine students remaining in the class took the same survey at the end of the course. The before and after scores for each of the nine students who completed the course are shown below. student before after 1 72 69 2 66 52 3 83 71

12/14/23, 5:00 PM Chapter 12 Correlation Concepts (counts towards your grade) https://egcc.instructure.com/courses/40375/assignments/1211295?module_item_id=3857986 9/9 Question 15 1/1 pt Details 4 97 85 5 95 61 6 78 45 7 95 56 8 52 43 9 93 62 Compute the correlation between before and after scores for these students. (Assume the correlation conditions have been satisfied and round your answer to the nearest 0.001.) .588 Question Help: Video Message instructor Here is a bivariate data set. x y 53 2 41 65 50 67 51 53 36 -21 61 27 46 21 Find the correlation coefficient and report it accurate to four decimal places. r = .2132 Hint: Help

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