Consider the following studies:

Study 1:A study reported in the British Medical Journal investigated the validity of Benjamin Franklin's maxim "early to bed and early to rise makes a man healthy, wealthy and wise". The study analysed data on men and women aged 65 and over for whom data on sleeping patterns, health, socioeconomic circumstances and cognitive abilities had been collected as part of a survey funded by the U.K. Department of Health and Social Security. 356 people were defined as "larks" (going to bed before 11pm and rising before 8am) and 318 people were defined as "owls" (going to bed after 11pm and rising after 8am).

Study 2:The manager of a plant that produces frozen meals wanted to compare two different recipes for making lasagne. 200 volunteers were recruited for a study. As it was known that there could be moderate differences in taste preferences for different racial groups, the volunteers were split into three groups: Maori/Polynesian, Asian and European. Each group was then randomly split into two, with half getting a lasagne made using the first recipe and the rest getting a lasagne made with the second recipe. After eating the lasagne, each volunteer was then interviewed and a taste score was recorded based on his or her answers to a series of questions.

(a)Answer the following questionsFOR EACHstudy:

(i)Identify the groups that are being compared. (I.e., what treatments or factors of interest

are being compared?)DO NOTalso say what is being measured to make the comparison - you do this in (ii).

(ii)What is being measured to compare these groups?ONLYdescribe the variable being measured.DO NOTalso mention the groups being compared - you do this in (i).

(iii)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 instead? If so, briefly explain how. If not, briefly explain why not.

(b)One concern with study 1 was that "the direction of cause and effect between wealth and sleeping pattern is not certain".

1. (i)Explain what is meant by "the direction of cause and effect".
2. (ii)Why can't the study establish the direction of cause and effect?

(c)Ignoring any concerns from (b), can we extend conclusions from study 1 to the population in general? Briefly justify your answer.[1 Mark]

(d)Which of the studies, if any, used blocking? For any studies in which blocking was used, describe what was blocked.[1 Mark]

(e)In which of the studies, if any, should blinding have been used? For any of these studies, describe to what extent blinding should be used.[1 Mark]