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regression questions to help in study for an exam
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In the following multiple-choice questions, select the best answer.
The correlation coefficient is used to determine: a. A specific value of the y-variable given a specific value of the x-variable b. A specific value of the x-variable given a specific value of the y-variable c. The strength of the relationship between the x and y variables d. None of these
If there is a very strong correlation between two variables then the correlation coefficient must be a. any value larger than 1 b. much smaller than 0, if the correlation is negative c. much larger than 0, regardless of whether the correlation is negative or positive d. None of these alternatives is correct.
In regression, the equation that describes how the response variable (y) is related to the explanatory variable (x) is: a. the correlation model b. the regression model c. used to compute the correlation coefficient d. None of these alternatives is correct.
The relationship between number of beers consumed ( x ) and blood alcohol content ( y ) was studied in 16 male college students by using least squares regression. The following regression equation was obtained from this study: != - 0.0127 + 0.0180 x The above equation implies that: a. each beer consumed increases blood alcohol by 1.27% b. on average it takes 1.8 beers to increase blood alcohol content by 1% c. each beer consumed increases blood alcohol by an average of amount of 1.8% d. each beer consumed increases blood alcohol by exactly 0.
SSE can never be a. larger than SST b. smaller than SST c. equal to 1 d. equal to zero
Regression modeling is a statistical framework for developing a mathematical equation that describes how a. one explanatory and one or more response variables are related b. several explanatory and several response variables response are related c. one response and one or more explanatory variables are related d. All of these are correct.
In regression analysis, the variable that is being predicted is the a. response, or dependent, variable b. independent variable c. intervening variable d. is usually x
Regression analysis was applied to return rates of sparrowhawk colonies. Regression analysis was used to study the relationship between return rate ( x : % of birds that return to the colony in a given year) and immigration rate ( y : % of new adults that join the colony per year). The following regression equation was obtained. ! = 31.9 – 0.34 x Based on the above estimated regression equation, if the return rate were to decrease by 10% the rate of immigration to the colony would: a. increase by 34% b. increase by 3.4% c. decrease by 0.34% d. decrease by 3.4%
In least squares regression, which of the following is not a required assumption about the error term ε? a. The expected value of the error term is one. b. The variance of the error term is the same for all values of x. c. The values of the error term are independent. d. The error term is normally distributed.
Larger values of r^2 ( R^2 ) imply that the observations are more closely grouped about the a. average value of the independent variables b. average value of the dependent variable c. least squares line d. origin
In a regression analysis if r^2 = 1, then a. SSE must also be equal to one b. SSE must be equal to zero c. SSE can be any positive value d. SSE must be negative
If two variables, x and y , have a very strong linear relationship, then a. there is evidence that x causes a change in y b. there is evidence that y causes a change in x c. there might not be any causal relationship between x and y d. None of these alternatives is correct.
If the coefficient of determination is equal to 1, then the correlation coefficient a. must also be equal to 1 b. can be either - 1 or + c. can be any value between - 1 to + d. must be - 1
In regression analysis, if the independent variable is measured in kilograms, the dependent variable a. must also be in kilograms b. must be in some unit of weight c. cannot be in kilograms d. can be any units
The data are the same as for question 4 above. The relationship between number of beers consumed ( x ) and blood alcohol content ( y ) was studied in 16 male college students by using least squares regression. The following regression equation was obtained from this study: != - 0.0127 + 0.0180 x Suppose that the legal limit to drive is a blood alcohol content of 0.08. If Ricky consumed 5 beers the model would predict that he would be: a. 0.09 above the legal limit b. 0.0027 below the legal limit c. 0.0027 above the legal limit d. 0.0733 above the legal limit
In a regression analysis if SSE = 200 and SSR = 300, then the coefficient of determination is a. 0. b. 0. c. 0. d. 1.
If the correlation coefficient is 0.8, the percentage of variation in the response variable explained by the variation in the explanatory variable is a. 0.80% b. 80% c. 0.64% d. 64%
If the correlation coefficient is a positive value, then the slope of the regression line a. must also be positive b. can be either negative or positive c. can be zero d. can not be zero
If the coefficient of determination is 0.81, the correlation coefficient a. is 0. b. could be either + 0.9 or - 0. c. must be positive d. must be negative
A fitted least squares regression line a. may be used to predict a value of y if the corresponding x value is given b. is evidence for a cause-effect relationship between x and y c. can only be computed if a strong linear relationship exists between x and y d. None of these alternatives is correct.
Regression analysis was applied between $ sales ( y ) and $ advertising ( x ) across all the branches of a major international corporation. The following regression function was obtained. ! = 500 0 + 7. 25 x If the advertising budgets of two branches of the corporation differ by $30,000, then what will be the predicted difference in their sales? a. $217, b. $222, c. $ d. $7.
Suppose the correlation coefficient between height (as measured in feet) versus weight (as measured in pounds) is 0.40. What is the correlation coefficient of height measured in inches versus weight measured in ounces? [12 inches = one foot; 16 ounces = one pound] a. 0. b. 0. c. 0. d. cannot be determined from information given e. none of these
Assume the same variables as in question 28 above; height is measured in feet and weight is measured in pounds. Now, suppose that the units of both variables are converted to metric (meters and kilograms). The impact on the slope is: a. the sign of the slope will change b. the magnitude of the slope will change c. both a and b are correct d. neither a nor b are correct
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37 .1 Use the formula to the right to compute the sample correlation coefficient: a. 0. b. - 0. c. 0 d. 1
37 .2 The least squares estimate of b 1 equals a. 0. b. 1. c. - 1. d. - 0. 37 .3 The least squares estimate of b 0 equals a. 0. b. 1. c. - 1. d. - 0. 37 .4 The sum of squares due to regression (SSR) is a. 1434 b. 505. c. 50. d. 928. 37 .5 The coefficient of determination equals a. 0. b. - 0. c. 0 d. 1 37 .6 The point estimate of y when x = 0.55 is a. 0. b. 2. c. 1. d. - 2. e. - 0. MULTIPLE CHOICE ANSWERS