Study 1: A marketing manager for a chain of 64 small bakeries was interested in how different special offers affected sales. 20 of the bakeries were randomly chosen to have a special offer where customers could purchase three loaves of bread for the price of two. 20 of the remaining bakeries were randomly selected to sell loaves of bread with a 20% discount. The remaining bakeries did not offer any discount. After a week, the total number of loaves of bread sold at each bakery was recorded.
Study 2: A road safety researcher was interested in the effects of alcohol on the driving ability of young adults. A sample of 50 young adults was obtained and each was randomly allocated to either an alcohol group or a no alcohol group. The members of the alcohol group each drank 700ml of beer then did a 10 minute session on a driving simulator. The members of the no alcohol group just did a 10 minute session on a driving simulator. For each member, the driving simulator reported the number of errors made during their 10 minute session.
(a)Answer the following questions FOR EACH study:
(i)Identify the groups that are being compared. (I.e., what treatments or factors of interest are being compared?) DO NOT also say what is being measured to make the comparison
â€“ you do this in (ii).
(ii)What is being measured to compare these groups? ONLY describe the variable being measured. DO NOT also mention the groups being compared â€“ you do this in (i).
(iii)Would you describe the study as an experiment or an observational study? Referring to the study design, justify your answer. (I.e., what part of the study design led you to this conclusion?)
[6 Marks total: 3 marks for each study]
(b)For Study 2, young adults had different drinking habit, with some being heavy drinkers, some
being moderate drinkers and some being mild drinkers. Describe how we could adjust the study
design to take advantage of this extra knowledge.[2 Marks]
(c)Could the results of a study such as Study 1 be used to argue that any overall difference in the number of loaves sold is as a result of the type of offer given to the shop? Briefly justify your answer.
(d)Did Study 1 have a control group? If so briefly describe the control group?