Semester Two Final Examinations, 2017 STAT1201 Analysis of Scientific Data AC THE UNIVERSITY OF QUEENSLAND AUSTRALIA Venue Seat Number Student Number Family Name This exam paper must not be removed from the venue First Name School of Mathematics & Physics EXAMINATION Semester Two Final Examinations, 2017 STAT1201 Analysis of Scientific Data This paper is for St Lucia Campus, Gatton Campus (External) and Gatton Campus students. Examination Duration: 120 minutes Reading Time: 10 minutes Exam Conditions: For Examiner Use Only Question Mark This is a Central Examination 1 This is a Closed Book Examination - specified materials permitted 2 During reading time - Write only on rough paper provided 3 This examination paper will be released to the Library Materials Permitted In The Exam Venue: 4 (No electronic aids are permitted e.g. laptops, phones) Calculators - Casio FX82 series or UQ approved (labelled) Total An annotated copy of A Portable Introduction to Data Analysis (any edition) is also permitted. Materials To Be Supplied To Students: None Instructions To Students: There are 52 marks available on this exam from 4 questions, each worth 13 marks. Write your answers in the spaces provided in pages 2-15 of this examination paper. Show your working and state conclusions where appropriate. Pages 16-20 give formulas and statistical tables. Those pages will not be marked. The textbook can have any amount of annotation on its pages. Loose sheets of paper or post-it notes are not permitted. Page tabs are allowed. Page 1 of 20
Semester Two Final Examinations, 2017 STAT1201 Analysis of Scientific Data Question 1 A study aimed to determine if grapefruit juice has beneficial effects on the pharmacokinetics of oral digoxin, a drug often prescribed for heart ailments. Seven healthy non-smoking volunteers participated in the study. Subjects took digoxin with water for 2 weeks, no digoxin for 2 weeks, and then digoxin with grapefruit juice for 2 weeks. The peak plasma digoxin concentrations (Cmax; ng/ml) when subjects took digoxin under the two conditions are given in the following table: Subject 1 2 3 4 5 6 7 Water Grapefruit Juice 3.03 3.46 Decrease -0.69 2.34 2.46 -1.00 1.87 1.97 -0.10 3.09 5.59 4.05 3.81 3.07 -0.72 2.52 1.43 6.21 2.62 3.44 2.77 While small, note that the sample size was chosen carefully by the authors. In their paper they state that "assuming an a level of 0.05, a sample size of seven subjects has a power of 85% to detect a 25% change in digoxin Cmax". Lower values of Cmax are better since they imply that digoxin is available in the body for longer. Is there any evidence that grapefruit juice increases the effectiveness of oral digoxin, by decreasing Cmax? (a) Identify one issue in the design of this experiment that undermines being able to use the data to answer this question. How could the design be improved? [2 marks] (b) Suppose u is the true mean decrease in digoxin Cmax with grapefruit compared to water. Define the null and alternative hypotheses for this study