Exam 26: Inferences for Regression

The sample data below are the index of exposure to radioactive waste for nine different geographic regions and cancer mortality rates (deaths per 100,000). Using a 1% level of significance,do the data below support the claim that a higher index of exposure is associated with a higher cancer mortality rate?

In a study of the relationship between weight and height,a sample regression equation is obtained,in which height is used as the predictor variable.This sample regression equation is then used to make inferences.Which of the following statements is true?

The typing speeds (in words per minute)and reading speeds (in words per minute)of nine randomly selected secretaries were recorded.Use the regression analysis and summary statistics provided below to determine a 90% prediction interval for the reading speed of a secretary whose typing speed is 50. Dependent variable is: Reading speed R-squared = 12.385% S = 100.3348 with 9 - 2 = 7 degrees of freedom

A grass seed company conducts a study to determine the relationship between the density of seeds planted (in pounds per 500 sq ft)and the quality of the resulting lawn.Eight similar plots of land are selected and each is planted with a particular density of seed.One month later the quality of each lawn is rated on a scale of 0 to 100.The regression analysis and summary statistics are given below.A 99% prediction interval for the lawn quality of a lawn sown with a seed density of 2.9 was determined to be (10.6,82.0). Dependent variable is: Lawn Quality R-squared = 36.0% S = 9.073602 with 8 - 2 = 6 degrees of freedom

Applicants for a particular job,which involves extensive travel in Spanish-speaking countries,must take a proficiency test in Spanish.The sample data below were obtained in a study of the relationship between the numbers of years applicants have studied Spanish and their score on the test. Using a 1% level of significance,do the data provide sufficient evidence to conclude that the slope of the regression line is not 0 and hence that number of years of study is useful as a predictor of score on the test?

Applicants for a particular job,which involves extensive travel in Spanish-speaking countries,must take a proficiency test in Spanish.The sample data below were obtained in a study of the relationship between the numbers of years applicants have studied Spanish and their score on the test.Use the regression analysis below to explain what the R-squared in this regression means. Dependent variable is: Score R-squared = 83.0% s = 5.65138 with 10 - 2 = 8 degrees of freedom

Applicants for a particular job,which involves extensive travel in Spanish-speaking countries,must take a proficiency test in Spanish.The sample data were obtained in a study of the relationship between the numbers of years applicants have studied Spanish and their score on the test.Use the regression analysis and summary statistics given below to find a 95% confidence interval for the average score of an applicant who has studied Spanish for 2.2 years. Dependent variable is: Score R-squared = 83.0% S = 5.65138 with 10 - 2 = 8 degrees of freedom

A grass seed company conducts a study to determine the relationship between the density of seeds planted (in pounds per 500 sq ft)and the quality of the resulting lawn.Eight similar plots of land are selected and each is planted with a particular density of seed.One month later the quality of each lawn is rated on a scale of 0 to 100.The regression analysis and summary statistics are given below.Determine a 99% confidence interval for the average lawn quality of a lawn sown with a seed density of 2.1. Dependent variable is: Lawn Quality R-squared = 36.0% S = 9.073602 with 8 - 2 = 6 degrees of freedom

Ten students in a graduate program at the University of Toronto were randomly selected.Their grade point averages (GPAs)when they entered the program were between 3.5 and 4.0.The data consist of the students' GPAs on entering the program and their current GPAs.Several graphs are shown below.

The typing speeds (in words per minute)and reading speeds (in words per minute)of nine randomly selected secretaries were recorded.Using a 10% level of significance,use the regression analysis provided below to determine if there is sufficient evidence of an association between typing speed and reading speed. Dependent variable is: Reading speed R-squared = 12.385% s = 100.3348 with 9 - 2 = 7 degrees of freedom

A grass seed company conducts a study to determine the relationship between the density of seeds planted (in pounds per 500 sq ft)and the quality of the resulting lawn.Eight similar plots of land are selected and each is planted with a particular density of seed.One month later the quality of each lawn is rated on a scale of 0 to 100.The sample data are given below. Using a 10% level of significance,is there evidence of an association between seed density and lawn quality?

In the context of regression analysis,explain what is meant by the term "residual".

The typing speeds (in words per minute)and reading speeds (in words per minute)of nine randomly selected secretaries were recorded.Use the regression analysis provided below to find a 90% confidence interval for the slope of the regression line. Dependent variable is: Reading speed R-squared = 12.385% S = 100.3348 with 9 - 2 = 7 degrees of freedom

Decide whether or not the conditions and assumptions for regression inference are satisfied. Explain your answer. -

Applicants for a particular job,which involves extensive travel in Spanish-speaking countries,must take a proficiency test in Spanish.The sample data were obtained in a study of the relationship between the numbers of years applicants have studied Spanish and their score on the test.Use the regression analysis given below to find a 99% confidence interval for the slope of the regression line. Dependent variable is: Score R-squared = 83.0% S = 5.65138 with 10 - 2 = 8 degrees of freedom

The index of exposure to radioactive waste and the cancer mortality rates (deaths per 100,000)were recorded for nine different geographic regions.A 95% prediction interval for the cancer mortality rate of a region whose index of exposure is 5.79 is 133.0 to 203.4 deaths per 100,000. Dependent variable is: Cancer Mortality Rate R-squared = 85.8% S = 14.00993 with 9 - 2 = 7 degrees of freedom

The index of exposure to radioactive waste and the cancer mortality rates (deaths per 100,000)were recorded for nine different geographic regions.A 95% confidence interval for the mean cancer mortality rate of all regions whose index of exposure is 6.57 was determined to be (162.5,188.2). Dependent variable is: Cancer Mortality Rate R-squared = 85.8% S = 14.00993 with 9 - 2 = 7 degrees of freedom

The sample data below are the typing speeds (in words per minute)and reading speeds (in words per minute)of nine randomly selected secretaries. Using a 10% level of significance,do the data provide sufficient evidence of an association between typing speed and reading speed?

Decide whether or not the conditions and assumptions for regression inference are satisfied. Explain your answer. -

Applicants for a particular job,which involves extensive travel in Spanish-speaking countries,must take a proficiency test in Spanish.The sample data were obtained in a study of the relationship between the numbers of years applicants have studied Spanish and their score on the test. Dependent variable is: Score R-squared = 83.0% S = 5.65138 with 10 - 2 = 8 degrees of freedom