Exam 7: Inferences About the Difference Between Two Means

A researcher collects data on shyness for two groups: 1) high school students who have their own cell phone; and 2) high school students who do NOT have a cell phone. Shyness is measured by the Shyness Inventory (an interval scaled variable). For group one (students who have their own cell phone), the following values are measured from the Shyness Inventory: 89, 95, 72, 68, 91, 86. For group two (students who do NOT have their own cell phone), the following values are measured from the Shyness Inventory: 56, 78, 61, 43, 80, 50. Conduct the appropriate statistical procedure at alpha of .05 to determine if there is a difference, on average, of the shyness of students who have versus do not have a cell phone. What is the p value?

A swim coach designs an experiment to determine if children who participate in group versus individual swim lessons have different swimming skills, on average. She randomly selects 20 children who have registered for swim lessons and randomly assigns them to group or individual swim lessons and collects data on the following: 1) type of swim lesson participated (two categories: group or individual); and 2) swimming skills (measured on a scale from 0 to 200). Her research question reads: Is there a mean difference in swimming skills for children who participate in individual versus group swimming lessons? Which of the following represents the DEPENDENT variable?

A researcher collects information on students enrolled in a statistics course to determine if their level of anxiety changes from the time they begin the course to the time they end the course. Lower scores on the instrument reflect decreased anxiety toward statistics. The pretest and posttest scores for the students were: 88, 94, 91, 84, 80, 76, 96, 90, 83, 95. The posttest scores were: 56, 64, 72, 80, 42, 40, 51, 32, 61, 59. (The data are in respective order. For example, for student A the pretest score was 88 and posttest score was 56; for student B the pretest score was 94 and posttest score was 64, and so forth.) Conduct the appropriate statistical procedure at alpha of .05 to determine if there is a difference in statistics anxiety, on average, prior to and after completion of a statistics course. What is the t test statistic value?

Interpret the following SPSS output in terms of the extent to which the assumption of normality has been met. Include appropriate evidence (e.g., statistical values from the output). a. Lilliefors Significance Correction *. This is a lower bound of the true significance.

Malani is examining the following research question: Is there a mean difference in the weight of garbage thrown away per week by homeowners as compared to renters? Use the 'Garbage' dataset. "Weight" is a ratio level measurement scale variable. "Own_Rent" is a nominal level measurement scale variable. Conduct the the appropriate inferential statistical procedure at an alpha level of .05. Do NOT exclude any cases when conducting the test. Which one of the following is correct based on reviewing the results of the test?

A recent article you read indicates that the p value for Levene's test for homogeneity of variances was .19. Which of the following is a correct interpretation based on this information?

A professor is examining success of tenure-track faculty in attaining tenure at their postsecondary institution. He surveys tenure-track faculty who have went through the tenure process in the past year and gathers data on two variables: 1) the number of publications in refereed journals (measured in whole numbers); and 2) whether or not they attained tenure (yes or no). The research question is: Is there an average difference in the number of publications based on faculty who attain tenure as compared to faculty who do not attain tenure? Which of the following represents the DEPENDENT variable?

In which one of the following is evidence of normality suggested?

A researcher collects data on shyness for two groups: 1) high school students who have their own cell phone; and 2) high school students who do NOT have a cell phone. Shyness is measured by the Shyness Inventory (an interval scaled variable). For group one (students who have their own cell phone), the following values are measured from the Shyness Inventory: 89, 95, 72, 68, 91, 86. For group two (students who do NOT have their own cell phone), the following values are measured from the Shyness Inventory: 56, 78, 61, 43, 80, 50. Conduct the appropriate statistical procedure at alpha of .05 to determine if there is a difference, on average, of the shyness of students who have versus do not have a cell phone. What is the t test statistic value?

Malani is examining the following research question: Is there a mean difference in the weight of garbage thrown away per week by homeowners as compared to renters? Use the 'Garbage' dataset. "Weight" is a ratio level measurement scale variable. "Own_Rent" is a nominal level measurement scale variable. Conduct the the appropriate inferential statistical procedure at an alpha level of .05. Do NOT exclude any cases when conducting the test. Which one of the following is correct based on reviewing eta squared calculated from the data?