Question

Question 5. 111 marks] (Chapter 2] Consider the following studies Study 1: A study was conducted to see if music can influence people's ability to remember Memory was tested by giving people a series of pictures to look at for 10 minutes and then asking them to answer a series of questions about the pictures. A memory score computed based on their answers. 120 people were recruited and randomly allocated to one of 4 groups: the first group did the memory test while listening to classical music; the second group listened to country and western music; the third group listened to heavy metal music while the fourth group did the test in silence. Study 2: The organiser of a major sporting event was interested in how many New Zealanders were willing to pay various prices for tickets to the final of the tournament. Lists of registered supporters of local clubs were gathered and then a sample of 1000 people were randomly selected from the list. Everyone in the sample was sent a letter stating the proposed price of tickets and asking them if they would be willing to purchase tickets at that price. The sample had been randomly split into two groups, with half getting a letter saying that the tickets cost $40 while the rest got a letter saying that the ticket price was $50. The proportion of people saying they would buy tickets was recorded for each group. (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 - you do this in (ii) What is being measured to compare these groups? ONLY describe the variable being measured. DO NOT also mention the groups being compared -you do this in (i) (ii) (ii) Would you describe the study as an experiment or an observational study? If it was an experiment, what part of the study design led you to this conclusion? - - If it was an observational study, could an experiment have been easily carried out [6 Marks total: 3 marks for each study] (b) Can we extend any conclusions from study 2 to the New Zealand population in general instead? If so, briefly explain how. If not, briefly explain why not. Briefly justify your answer. 12 Marks) (c) Did either of th e studies use control groups? If so, describe the control group and wh ether or not the control group received placebos 13 Marks)

Answer 1

a)

i)

In Study 1 we are studying impact of music (Group 1 = Classical Music, Group 2 = Country & Western Music, Group 3 = Heavy metal Music and Group 4 = No Music) on people’s ability to remember.

In Study 2 we are studying impact of price (Group 1 being 40$ and Group being 50$) on ticket purchasing.

ii)

In Study 1 memory score was being measured

In Study 2 proportion of people willing to memory score was being measured

iii)

• In an observational study, we measure or survey members of a sample without trying to affect them.
• In a controlled experiment, we assign people or things to groups and apply some treatment to one of the groups, while the other group does not receive the treatment.

So, Study 1 is an experimental study. Since we divided all people into 4 Groups and each group was treated (music) differently, this clearly identified the study as an experimental study.

Study 2 is an observational study. No we cannot conduct an experiment study as there is no treatment effect in this study ie we are just recording the response of people ie whether they want to buy the ticket or not.

b)

Yes, we can extend the conclusions of Study 2 to the New Zealand population since we the data will follow normal behaviour ( sample size is large enough (ie greater than 30) for the data to show normality)

c)

Yes, Study 1 used control groups. Control Groups are various groups ie Group 1 = Classical Music, Group 2 = Country & Western Music, Group 3 = Heavy metal Music and Group 4 = No Music.

Yes the control groups received placebo as Group 4 is the placebo.