Test 3 CIT 32000 Altom Spring 2012 Name _______________________________________ Important Notes: • There are parts of the test that rely on material I covered in class, and may not appear in the book. • In cases where I ask you for explanations or interpretations, I am prepared to accept a wide range of views if you can provide a strongly reasoned argument. You must convince me. Present whatever evidence seems compelling. • Use these pages as scratch paper. Show your work on all problems. Use the backs of the pages if necessary. • Calculators and stats software may be used, but show your work wherever possible. I give partial credit for thinking through problems even if they have the wrong answer. • Remember to read the problem carefully before beginning. Be meticulous and think carefully. • Return this test promptly. It must be in my hands by the beginning of the class period when it is due. I cannot accept late submissions.
Test 3, CIT 32000, Spring 2012 Altom P. 2 For each of the following, state which test is most appropriate to the situation. Be sure to specify the exact test. For example, a paired t-test would not be appropriate in the same circumstances as an independent t-test. And keep in mind that “test” may apply to a wide range of procedures. 1. A study is conducted to determine if time of day has any effect on test grades. An introductory psychology class is selected for the study, because it has a standard curriculum taught across many sections. Two classes are selected for each time period: 8:00 AM, 1:00 PM, and 5:30 PM. Out of the total pool of around 40 students for each time period, 15 students are selected at random, for a total of 45. The test is administered to all students, and the test results for the study subjects are placed in SPSS. We want to know if there is a statistical difference between these time periods. What test is appropriate? _____________________________________________________________________(5 pts) 2. Hicks law predicts how long it will take a user to pick out a given element on a website page from among all the other elements on that page. Because a certain website will be used many thousands of times per year on an intranet, a major company engages a usability specialist to test whether the Hicks prediction holds on two proposed home page designs. Because the company is reluctant to have too many employees absent from work stations, it specifies that the test can involve only five individuals, and that therefore the same five people must test both proposed interfaces. We will want to know if there is a significant difference in the times for each interface. What is the appropriate test? _____________________________________________________________________(5 pts) 3. Laparoscopic surgery is a procedure for threading a small flexible tube within a patient’s body to explore or perform procedures. A recent study was conducted to see what skills a medical student new to laparoscopic surgery might have that would predict shorter learning times. One variable that was gathered was the amount of time a student had spent playing video games before starting his laparoscopic training. The researcher wants to see if the time spent gaming can predict the time needed to perfect laparoscopic skills. What would be the correct test to apply? _____________________________________________________________________(5 pts) 4. A large company is concerned about turnover, so it commissions a survey that will be given to a random group of 1000 employees. The company then wants to get a general idea of what the results would be in the larger population, but while it will look at significance indicators, it is not heavily interested in significance, but in an estimate of company-wide results. What test would be proper to run here? _____________________________________________________________________ (5 pts)
Test 3, CIT 32000, Spring 2012 Altom P. 3 A study is conducted into time missed from work, compared with outside temperature. A random sample of 50 employees is extracted from the human resources attendance database and a correlation is conducted. There is found to be an r of .311 at an alpha of .05, two-tailed. 5. What is the critical value of r? _____________________________________________________________________ (5 pts) 6. Is the test r significant? ______________________________________________________________________(5 pts) Refer to the table below. It gives two sets of figures, a predicted rainfall amount from a radar image, and an actual rainfall amount as measured by a standard rain gauge. (X) Radar Rain Prediction(Y) Rain Gauge3.6 .0 2.0 1.2 1.1 1.2 1.3 1.3 1.8 1.4 2.1 1.4 3.2 2.0 2.7 2.1 2.5 2.5 3.5 2.9 3.9 4.0 3.5 4.9 6.5 6.2 7.3 6.6 6.4 7.8