Quiz: Correlation

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1. The points in the scatterplot show a
a. strong positive relationship
b. strong negative relationship
c. weak positive relationship
2. The points in the scatterplot would have a correlation coefficient near
a. –0.9
b. 0
c. 0.9
3. The possible values for the correlation coefficient are
a. –1 ≤ r ≤ 1
b. 0 ≤ r ≤ 1
c. 0 ≤ r ≤ 10
4. The pairs in a data set are changed from feet to inches, so all values are multiplied by 12. The correlation coefficient for the new data will be
a. 12 times larger than the original
b. 144 times larger than the original
c. the same as the original
5. The pairs in a data set are exchanged, so the x-coordinates are now the y-coordinates and all values are multiplied by 12. The correlation coefficients for the original data and for the new data are
a. opposites
b. reciprocals
c. the same
6. A correlation coefficient of 0.5 suggests that
a. each y-coordinate is about half of the x-coordinate
b. as x increases, y also increases
c. as x increases, y decreases
7. A set of paired data has n = 5, Σ x = 15, Σ y = 27, Σ xy = 100, sx = 2, and sy = 3. The correlation coefficient is about
a. –0.8
b. 0.79
c. 0.96
8. A set of paired data has n = 27 and r = 0.60. A test of H0: ρ = 0 vs. Ha: ρ ≠ 0 is conducted. The degree of freedom is
a. 25
b. 26
c. 27
9. A set of paired data has n = 27 and r = 0.60. A test of H0: ρ = 0 vs. Ha: ρ ≠ 0 is conducted. The test statistic is
a. 0.60
b. 3.0
c. 3.75
10. A set of paired data has n = 27 and r = 0.60. A test of H0: ρ = 0 vs. Ha: ρ ≠ 0 is conducted, where ρ represents the population proportion. The p-value is
a. less than 0.001
b. between 0.001 and 0.0025
c. between 0.0025 and 0.005
11. If a test of H0: R = 0 vs. Ha: R ≠ 0 has a p-value less than the chosen α value there is evidence that the data has
a. no linear relationship
b. no relationship of any kind
c. a linear relationship
12. If the correlation coefficient is 0.81, then the coefficient of determination is
a. 0.6561
b. 0.81
c. 0.90
13. If the coefficient of determination is 0.70, then
a. about 70% of the data is explained by the linear relationship.
b. about 70% of the correlation is explained by the linear relationship.
c. about 70% of the variation in y is explained by the linear relationship.
14. If the coefficient of determination is 0.64, then the correlation coefficient
a. must be –0.80
b. might be –0.80 or 0.80
c. must be 0.80

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