math QAs

MAT 240 – Applied Statistics Spring 2016

Computer Project:

Two-Sample Hypothesis Tests in Minitab Express

For this project, you will apply your understanding of hypothesis testing to three applications. You will

use Minitab Express software to perform hypothesis tests to answer the primary research question for

each of the three scenarios given.

Instructions for performing two-sample hypothesis tests and confidence intervals in Minitab Express are

posted in the Projects section of Blackboard in the file:

InstructionsTwo-SampleHypothesisTestsInMinitabExpress.Pdf.

Prepare a separate report with your answers to the questions for each of the three problems below. Be sure

to include any statistics and/or graphs to support your answers and claims about the problems. An outline

for how your work will be assessed (called a grading rubric) is in the Project 3 folder under the Projects

menu on Blackboard. Data files for problems 2 and 3 are also located in the Project 3 folder under the

Projects menu on Blackboard.

Problem 1: Does lovastatin (a cholesterol-lowering drug) reduce the risk of heart attack? In a Texas

study, researchers gave lovastatin to 2,450 people and an inactive substitute to 2,370 people (average age

58). After 5 years, 58 of the lovastatin group had suffered a heart attack, compared with 97 for the

inactive pill.

1) Check whether the conditions for conducting a hypothesis test are met. For each condition, give an explanation as to why it is met or why it wasn’t met.

2) State the null and alternative hypotheses for a hypothesis test of the sample data.

3) Using Minitab Express, conduct a hypothesis test (use  = 0.01) even if the conditions are not met.

4) What is the p-value for the hypothesis test?

5) State the conclusion.

Problem 2: Researchers at the University of Utah (Strayer and Johnston, 2001 † ) asked 16 student

volunteers to use a machine that simulated driving situations. At irregular intervals, a target would flash

red or green. Participants were instructed to press a “brake button” as soon as possible when they detected

a red light. The machine would calculate the mean reaction time to the red flashing targets for each

student in milliseconds.

The 16 students were given a warm-up period to familiarize themselves with the driving simulator. Then

the researchers had each student use the driving simulation machine while talking on a cell phone about

politics to someone in another room and then again with music or a book-on-tape playing in the

background (control). The students were randomly assigned as to whether they used the cell phone or the

control setting for the first trial. The data for the 16 students is in the file: CellPhoneReactionTimes.xls 

Does cell phone use make reaction times longer?

1) Check whether the conditions for conducting a hypothesis test are met. For each condition, give an explanation as to why it is met or why it wasn’t met.

2) State the null and alternative hypotheses for a hypothesis test of the sample data.

3) Using Minitab Express, conduct a hypothesis test (use  = 0.01) even if the conditions are not met.

4) What is the p-value for the hypothesis test?

5) State the conclusion.

Problem 3: In a 2001 study, Scott Keats 1 looked for a possible relationship between marijuana smoking

and a deficit in performance on a task measuring short term memory: the digit span task from the

Wechsler Adult Intelligence Scale. The researcher suspected that those who smoke marijuana regularly

will perform lower on the digit span task. Two groups of ten subjects were tested. One group, the

“nonsmokers,” claimed not to smoke marijuana. A second group, the “smokers,” claimed to smoke

marijuana regularly. Results of the tests are in the file: PotSmoking.xls. Do people who smoke marijuana

regularly perform lower on the digit span task than non-pot-smokers? Test at  = 0.05.

1) Check whether the conditions for conducting a hypothesis test are met. For each condition, give an explanation as to why it is met or why it wasn’t met.

2) State the null and alternative hypotheses for a hypothesis test of the sample data.

3) Using Minitab Express, conduct a hypothesis test even if the conditions are not met.

4) What is the p-value for the hypothesis test?

5) State the conclusion.

† Strayer, D. and Johnston W., (2001). “Driven to distraction: Dual-task studies of driving and conversing on a cellular

telephone,” Psych. Science, 21, p. 462-466.  Data taken from Agresti, A., and Franklin C. (2009), Statistics: The art and science of learning from data, 2

nd edition,

Pearson, New Jersey, p. 488 & 502. 1 Data were obtained from Coastal Carolina University: http://ww2.coastal.edu/kingw/statistics/R-tutorials/independent-t.html