Chapter 1. Measuring linear association: correlation

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Question 1

0:37

Question 1.1

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Correct. The cloud of data in the scatterplot on the left is skinnier than the cloud of data in the plot on the right. Note that the labeling on the x- and y-axes are the same for both scatterplots.
Incorrect. The cloud of data in the scatterplot on the left is skinnier than the cloud of data in the plot on the right. Note that the labeling on the x- and y-axes are the same for both scatterplots.
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Question 2

1:00

Question 1.2

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Correct. If you note the labeling on the x- and y-axes, you will see that the same data is plotted in both scatterplots.
Incorrect. If you note the labeling on the x- and y-axes, you will see that the same data is plotted in both scatterplots.
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Question 3

1:33

Question 1.3

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Correct. This is a hard question as the cloud of data in the plot on the right is much skinnier than the cloud of data in the plot on the left. However, both clouds are parallel to the x-axis. The line drawn through both clouds would have zero slope—indicating no relationship between X and Y.
Incorrect. This is a hard question as the cloud of data in the plot on the right is much skinnier than the cloud of data in the plot on the left. However, both clouds are parallel to the x-axis. The line drawn through both clouds would have zero slope—indicating no relationship between X and Y.
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Question 4

2:37

Question 1.4

L31GqwFXKQwnOh4zcFrDfffkzacRKfjxO/ljkO8G7y6jyptkZCw5LiAXWWbyJuzFzxennwbWoKifIkRqqTieMzpaJELK0k4ZrbfHnECeY8WPxTrJBVbytoEnrb65Sc0Y5B4NRKkINXSce3Wwbu6gCSHIQ+2mqro+CeaqfSNC+8YP6SNafcaQpRDpJ3fcSL8L9jkxrToRCqJwVyQ4NrFjp8BAFQs=
Correct. Computing correlation, r, requires both X and Y to be quantitative.
Incorrect. Computing correlation, r, requires both X and Y to be quantitative.
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Question 5

3:01

Question 1.5

Rq/xt7QGaBF8sGnIu4ZLhwHH4jksJw1jkzvtiXY5r+H997wuhyw+QQMb3Qv41vWH/fOHTftILzQfbPX47fG8Q8aZTaWzMkJ5NeHNBip/PIQPwTEbiBYBs8WGj00ICG/MJ9DZZsgO2KtYrId7snstTPeFLeOYUzSgaafCwSvQmdK/SxqmUHq3wMlGJgHMbSKaiI2WyQeBeJ8wYSC8VLP52LrjwStFWBdPi7KQ1RsyLWjkMvTMzGhe2p2v7e5m1/3wO16+VJfB/lVNu1G/PAaAGa2ZQ265zyAExvDNRhm8mNuLbrTtalKlQASe9Oo=
Correct. Correlation should only be computed for X and Y when their relationship is linear.
Incorrect. Correlation should only be computed for X and Y when their relationship is linear.
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Question 6

3:48

Question 1.6

8jz2kxTYXJ/DClPfZEUv3sKvtHIWSThJenYLgpnyAtxTLZh/0gTkgSeiVeBcOs/e+WpIMskIaq5qoMNrl1lBgd26VWmN5IB6v+NrtvyCdTWRcTBnF/Iawyz1b/fzsGkP4azXpw==
Correct. This is a correct statement.
Incorrect. This is a correct statement.
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Question 7

5:27

Question 1.7

SMnTodDewWW6jUdeViMLYxaZHDuPIiA3+Ex5CrF+HTOmEmhdAlFUrohom90mRMdU0I1j0pKy4ZNkVi/K1HMrqKOThcBcevNcaWsdPtvEAiT0mEyNAsECeRA+hggXaGYUgnQzh904Jm0qqs6MvZm7q8Og+EhSOuBdX3Qjsq5vhq0FaC6XN6DV3fOKNbaqt0v5Qpw9j1vKMxPUZIVNq4wscg==
Correct. While not strong, the direction of a line drawn through the cloud of data would have negative slope.
Incorrect. While not strong, the direction of a line drawn through the cloud of data would have negative slope.
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Question 8

6:40

Question 1.8

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Correct. z-scores can be negative or positive. A positive z-score multiplied by a negative z-score gives a negative product.
Incorrect. z-scores can be negative or positive. A positive z-score multiplied by a negative z-score gives a negative product.
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Question 9

7:23

Question 1.9

HG5iK3elq2rBBwwdwAvkqwglqUi+yR3fJ2w57bb7M6FBD+BW+HoRsUC8+mZsNPzWidj13peA1QpIEFbUNw1g3O7t8h6PB8IR38RM6xCBsOPVV6J/uKtjYEXpnPwJ9KMp9ICLFAnHfHrXJrE/PoYuisiqlcw+3h5WrJ/xLQnSulmUkCTUqTiAGA==
Correct. This is a correct statement.
Incorrect. This is a correct statement.
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Question 10

7:47

Question 1.10

SkGR1vzvaE0BrSGY6Oo9DJePx1jv88mlff0WT0l32juG0xSCMksSY0m9d8MEJ5Y59t6oXf/Tr53Qg6mVqjAT1gwuiI+PAbYHJBe7/VYVswoGD2hthwcjiO4tS6L5LviFeVBnKX55NngXghzOeOY2shN8aT0jllHt
Correct. On a scale from zero to one, 0.54 is near the middle so it tells us that the strength is “moderate.”
Incorrect. On a scale from zero to one, 0.54 is near the middle so it tells us that the strength is “moderate.”
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Question 11

9:10

Question 1.11

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Correct. This is a correct statement. All rectangles have red or pink colors.
Incorrect. This is a correct statement. All rectangles have red or pink colors.
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Question 12

9:47

Question 1.12

WKR0fWBC7feBfBHGTI+HHOlgF70uyBmv0fkJBxZuDiiseHPHXVs+Z0XdvgzowqykQmT7/6KPL1oJNBNEDJGMoSH3NZvglxSzw1iN2Y4pJs+9Ta7RXceyFyrynTCIFfl/0tKMoUfAa5DbxTdw2iFRM56Q7CdRAbuW66rpByPcjcvq5mQb5iw/EvWsgejdN3zFt++Plxbs3nnyW6TmbXol1i5AF5Cu6kGP3ZcD4oPENXGCAeYhjmI3rF2XK74R/Ps824ugYBc6irjp2jUm8+gbhIiLZoQ2lgGuZcNrbgXrRXu3HBCOMI8WZquKRsEGZxwQYH5B7NLwjf5DYEb+TM52ULBjqw7wcLsBV6p9p0E4t9pBxaO7nuQrMl52vdEkpqp8IXK4Eo1mNX/+O5brwhI8gGpsOyxY0haoYZ/l6TpCdlLdw5tgCy51y/yEF3yyXzXKthVCsvq8OeX7Q9VxV7+KV1P0wdLpzHEP
Correct. Since most of the rectangles have pink or red colors rather than blue colors, most of the products are positive.
Incorrect. Since most of the rectangles have pink or red colors rather than blue colors, most of the products are positive.
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Question 13

9:59

Question 1.13

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Correct. The number of rectangles with pink and red colors is about the same as the number of rectangles with blue colors.
Incorrect. The number of rectangles with pink and red colors is about the same as the number of rectangles with blue colors.
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Question 14

10:08

Question 1.14

64TNu9pWzNFGypbEbSm4k7+xeTrav0eoyWVL7691QIjBleb+zcvwUBXeEwAsfvLxdtHCKe7mLzzusP7ybnFCgGOaWef2tKuvF5tqTDPHNDiF3uxxCtM3eAoSA2XkjDTFH/sHniSA2P3haalgwBUFAOhe+ZeOQzWAYuUzIEbKZIIXrCMbIv5LPHhcCGDozK2EN8eS5SHB2yTfaPosJHi1u8lmree70ef2PVTQxGH70+RwCVCkbICmAdg3rjqlmn+uXqfQPXDF1NXtvdwrBjX7mVhfjS8BTVTWf0uwSDjnvyL8V1Ey5hUbJpwTFAjpyXveQVM9iRpDBJKQg39Za9k5RPuUGO64Vj9BFzx9x7Ezo1JfFtlrH7QgjQpUePgeXcvaiFfQ9pshUQexrPSvR+L3Hwqb/5kXa+03lS6Ewy/nKQWK2gr11dzi6RKgDu8zvGKwKyxdHZJiPqdDfIOiodfICymT6pKL/3Ja
Correct. The number of rectangles with red and pink colors is less than the number of rectangles with blue colors.
Incorrect. The number of rectangles with red and pink colors is less than the number of rectangles with blue colors.
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Question 15

10:27

Question 1.15

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Correct. All rectangles have blue colors.
Incorrect. All rectangles have blue colors.
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Question 16

11:26

Question 1.16

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Correct. This is a correct statement.
Incorrect. This is a correct statement.
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Questions 17-18

12:00

Question 1.17

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Correct. Since the sign on “r” is positive, direction is positive.
Incorrect. Since the sign on “r” is positive, direction is positive.
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Question 1.18

lHZ/4ZgsLwuEDxxsAgMxVF+FXPl4WSRbtvSm0JhvdxGTiyeiNZ2SVeLoxAGibYmRp4oA86ktCZgt4D/aC2r7wpHjhHGJsEXE2l4Nqz4gbf6rpH8pVyxZbbNNLjw=
Correct. Since “r” is very close to “+1.0,” the strength is really strong.
Incorrect. Since “r” is very close to “+1.0,” the strength is really strong.
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Questions 19-20

12:35

Question 1.19

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Correct. Since the sign on “r” is negative, direction is negative.
Incorrect. Since the sign on “r” is negative, direction is negative.
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Question 1.20

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Correct. On a scale from zero to one, 0.553 is about halfway in between, so strength is moderate.
Incorrect. On a scale from zero to one, 0.553 is about halfway in between, so strength is moderate.
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Question 21

13:49

Question 1.21

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Correct. Since the sign on “r” is negative, direction is negative.
Incorrect. Since the sign on “r” is negative, direction is negative.
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Questions 22-23

14:05

Question 1.22

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Correct. On a scale from zero to one, 0.226 is close to zero, so strength is weak.
Incorrect. On a scale from zero to one, 0.226 is close to zero, so strength is weak.
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Question 1.23

Scatterplot image
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Correct. First of all, a line drawn through the data will have positive slope, so “r” must also be positive. Second, there is too much scatter for “r” to be as high as 0.98. Of the answers given, 0.63 is the most reasonable.
Incorrect. First of all, a line drawn through the data will have positive slope, so “r” must also be positive. Second, there is too much scatter for “r” to be as high as 0.98. Of the answers given, 0.63 is the most reasonable.
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