Example Answer for Question 18 Paper 2: A Level Psychology, June 2017 (AQA)
Last updated 25 Apr 2018
Section C – Research Methods: Q18 [3 Marks]
One extraneous variable that could have affected the results is the time of day that the participants completed their 400m run. If some participants completed their run in the morning (when they are arguably more alert and have more energy) and some completed their run in the evening, this could have resulted in some participants running faster/slower than usual, therefore affecting the validity of results.
To control this extraneous variable, the participants should complete both conditions at roughly the same time of day (e.g. in the morning after breakfast, between 9 am and 11 am), to ensure that the time of day does not affect the results.
Please Note: These answers have been produced without the knowledge of the mark scheme and merely reflect my attempt at producing a model answer on the day of the exam.