A sports scientist wanted to investigate whether consuming beetroot juice improves aerobic performance during a middle-distance run.
The scientist recruited 15 experienced club runners for a study using a repeated measures design. In Condition A, participants drank 200 ml of concentrated beetroot juice 2 hours before a 400m time trial. In Condition B, participants drank 200 ml of a taste-matched placebo juice (which did not contain the active nitrates of beetroot) 2 hours before a 400m time trial.
To allow for a wash-out period, the two trials were conducted exactly one week apart at 09:00 AM on an outdoor running track. The scientist recorded the time taken (in seconds) to complete each 400m run.
Identify one extraneous variable that could have affected the results of this study. Suggest why it would have been important to control this extraneous variable and how it could have been controlled in this study.
Practise AQA A Level Psychology Scientific processes with exam-style questions for A Level Psychology. 689 questions, matched to the AQA A Level Psychology (7182) specification and written in Paper 1, Paper 2 and Paper 3 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.
