Mr. Rogers  AP Statistics Objectives

AP Statistics Practice Test Regression Chapter 3  
1  )  When we say that a regression line explains a fraction of the variation in the ydata, where is the variation measured from? 
2  )  Bob looks at a regression analysis with an rsquare of 0.20, a slope of .00012, and an intercept of 12, and concludes there is definitely no relationship between the variables. Is this a proper conclusion? Explain. 
3  )  Suppose the slope of a regression line is 7 and r = 0.50. If 3 is added to each explanatory (x) and response (y) data point, what will the new slope and r be? 
4 
)  Suppose the slope of a regression line is 7 and r =.50. If 3 is added only to each explanatory (x) data point data point, what will the new slope and r be? 
5  )  If the slope of a regression line is 5 and each explanatory (x) and response (y) data point is multiplied by .06 what is the new slope and r ? 
6 
)  If the slope of a regression line is 5 and each response (y) data point is multiplied by 0.06 what is the new slope and r ? 
Use the following data for 7 thru 12: xbar =10; Yhat = 40 x 20; r = .80; Range of xdata used for regression analysis = 0 to 20. x represents pounds of fertilizer and y represents bushels of corn,  
7  )  Find: ybar: slope; intercept; % of the variation in the ydata explained by the regression equation 
8  )  If x = 6 y = ? 
9  )  If x is raised by 10 what is the increase in y ? 
10  )  If x represents pounds of fertilizer and y represents bushels of corn, how many bushels of corn will be harvested if no fertilizer is applied? 
11  )  Ken the farmer looks at the regression analysis and decides to apply 700 lbs. of fertilizer to his garden in order to get a really big tomato crop. What is wrong with his analysis? 
12  )  You as a high priced consultant look at the residual plot for the above regression and can detect no pattern in the residuals. How do you interpret this? 
13  )  When r = 0 is there definitely no relationship between the variables? 
14  )  How is the regression line represented on a residual plot? 
15  )  The sum of the residuals for least squares regression analysis is always ___________. 
16  )  A researcher wants to find the relationship between mass and length for rattle snakes. She performs regression and correlation analysis with mass in units of kilograms and length in meters. She decides to rerun the analysis using pounds and inches. What parts of the regression and correlation analysis output will change? 
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