# D sse 79 what does the coefficient of determination r

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D. SSE 79. What does the coefficient of determination ( r 2 ) signify? D. The proportion of total variation that is explained 80. The coefficient of determination represents the ratio of SSR to SST. True 81. The standard error of the estimate is a measure of which of the following? A. The variation around the sample regression line. 82. In performing a regression analysis involving two numerical variables, you are assuming which of the following statements? I. That the variances of X and Y are equal. II. That the variation around the line of regression is the same for each X value. III. That X and Y are independent. A. II only 83. Data that exhibit an autocorrelation effect violate the regression assumption of independence. True 84. The residuals represent which of the following? C. The difference between the actual Y values and the predicted Y values. 85. If the plot of the residuals is fan shaped, which assumption is violated? D. Homoscedasticity 86. Regression analysis is used for prediction, while correlation analysis is used to measure the strength of the association between two numerical variables.

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True 87. If the correlation coefficient ( r ) is equal to 1.00, then which of the following must be true? B. There is no unexplained variation. 88. If the correlation coefficient ( r ) is equal to 1.00, then which of the following must be true? D. All the data points must fall exactly on a straight line with a positive slope. 89. Assuming a linear relationship between X and Y , if the coefficient of correlation ( r ) is equal to minus− 0.30, then which of the following must be true? D. The slope ( b 1 ) is negative. 90. The strength of the linear relationship between two numerical variables may be measured by which of the following? D. The coefficient of correlation 91. In a simple linear regression problem, which of the following must be true about r and b 1 ? C. They must have the same sign. 92. When r =minus−1, it indicates a perfect relationship between X and Y . True 93. A zero population correlation coefficient between a pair of random variables means that there is no linear relationship between the random variables. True 94. The management of a chain electronic store would like to develop a model for predicting the weekly sales (in thousands of dollars) for individual stores based on the number of customers who made purchases. A random sample of 12 stores yields the results shown in the accompanying table. Which is the correct null hypothesis for testing whether the number of customers who make a purchase affects weekly sales? C. H 0 : β 1 =0 95. It is believed that GPA (grade point average, based on a four point scale) should have a positive linear relationship with ACT scores. Given below is the technology output for predicting GPA using ACT scores based a data set of 8 randomly chosen students from a university.

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