Exam 14: Inference for Regression

A sales manager was interested in determining if there is a relationship between college GPA and sales performance (number of units sold in the previous month) among Salespeople hired within the last year.The estimated regression equation fit to the data Was found to be significant at α = 0.05.The 95% confidence interval for the number of Units sold when GPA = 3.00 was determined to be 20.914 to 22.657.The correct Interpretation is

An operations manager was interested in determining if there is a relationship between the amount of training received by production line workers and the time it takes for them To trouble shoot a process problem.A sample of recently trained line workers was Selected.The number of hours of training time received and the time it took (in minutes) For them to trouble shoot their last process problem were captured.A regression equation Was fit to the data and the following histogram of residuals obtained. Based on this histogram we can say

As the carbon content in steel increases, its ductility tends to decrease.A researcher at a steel company measures carbon content and ductility for a sample of 15 types of Steel.The estimated regression equation fit to the data was found to be significant at α = 0)05.The 95% prediction interval for the ductility of steel with 0.5% carbon content was Determined to be 0.45 to 11.59.The correct interpretation is

As the carbon content in steel increases, its ductility tends to decrease.A researcher at a steel company measures carbon content and ductility for a sample of 15 types of steel. Based on these data he obtained the following regression results. The standard error of the regression slope is

An operations manager was interested in determining if there is a relationship between the amount of training received by production line workers and the time it takes for them To trouble shoot a process problem.A sample of recently trained line workers was Selected.The number of hours of training time received and the time it took (in minutes) For them to trouble shoot their last process problem were captured.A regression equation Was fit to the data and the following residual plot obtained. Based on this plot, we can say

An operations manager was interested in determining if there is a relationship between the amount of training received by production line workers and the time it takes for them To trouble shoot a process problem.A sample of 15 recently trained line workers was Selected.The number of hours of training time received and the time it took (in minutes) For them to trouble shoot their last process problem were captured.The regression output Is shown below. The 95% confidence interval for the slope of the regression equation is

As the carbon content in steel increases, its ductility tends to decrease.A researcher at a steel company measures carbon content and ductility for a sample of 15 types of steel Resulting in a correlation of -0.640.The calculated value of the t-statistic to test for a Significant association between carbon content and ductility is

A researcher decides to investigate his students' suspicions that longer essays receive better scores on the SAT exam.He gathers data on the length of essays (number of lines) And the SAT scores received for a sample of students enrolled at his university.Based on 14-26 Chapter 14 Inference for Regression His regression results, the 95% confidence interval for the slope of the regression equation Is -0.88 to 1.34.At α = 0.05, we can say

Here is a plot of residuals versus fitted values: Based on the plot, we can say that

A sales manager was interested in determining if there is a relationship between college GPA and sales performance among salespeople hired within the last year.A Sample of recently hired salespeople was selected the number of units each sold last Month recorded.The correct null hypothesis is

Here is a plot of residuals versus fitted values.

A sales manager was interested in determining if there is a relationship between college GPA and sales performance among salespeople hired within the last year.A Sample of recently hired salespeople was selected the number of units each sold last Month recorded.The regression results are shown below. Based on these results, the residual standard deviation is

An operations manager was interested in determining if there is a relationship between the amount of training received by production line workers and the time it takes for them To trouble shoot a process problem.A sample of recently trained line workers was Selected.The number of hours of training time received and the time it took (in minutes) For them to trouble shoot their last process problem were captured.The estimated Regression equation fit to the data was found to be significant at α = 0.05.The 95% Prediction interval for trouble shooting time with 8 hours of training was determined to Be 12.822 to 19.261.The correct interpretation is

As the carbon content in steel increases, its ductility tends to decrease.A researcher at a steel company measures carbon content and ductility for a sample of 15 types of steel. Based on these data he obtained the following regression results. The 95% confidence interval for the slope of the regression equation is

A sales manager was interested in determining if there is a relationship between college GPA and sales performance among salespeople hired within the last year.A Sample of recently hired salespeople was selected the number of units each sold last Month recorded.The regression results are shown below. Based on these results, at α = .05 we will

An operations manager was interested in determining if there is a relationship between the amount of training received by production line workers and the time it takes for them To trouble shoot a process problem.A sample of recently trained line workers was Selected.The number of hours of training time received and the time it took (in minutes) For them to trouble shoot their last process problem were captured.The regression output Is shown below. 14-30 Chapter 14 Inference for Regression At α = .05, we will

An operations manager was interested in determining if there is a relationship between the amount of training received by production line workers and the time it takes for them To trouble shoot a process problem.A sample of recently trained line workers was Selected.The number of hours of training time received and the time it took (in minutes) For them to trouble shoot their last process problem were captured. Based on the scatterplot of the data shown, we can say that

A sales manager was interested in determining if there is a relationship between college GPA and sales performance among salespeople hired within the last year.A Sample of recently hired salespeople was selected the number of units each sold last Month recorded.The regression results shown are below. Based on these results, the percentage of variability in sales performance (units sold per Month) accounted for by college GPA is