• Extraneous variables and confounding variables.
  • The use of control groups, counterbalancing, randomisation and order effects.
  • Experimenter effects, demand characteristics and control issues.

Past Paper Questions

  • Define the term ‘randomisation’. (1) January 2020
2 Markers
  • Explain one participant variable that Manon may need to consider when planning her research. (2) January 2018
  • Explain how one participant variable could have affected Zulikhat’s study. (2) June 2019
  • Describe one control that researchers would have considered for the memory game used in this experiment. (2) January 2020
4 Markers
  • Explain two controls the researcher may have considered when planning this experiment that tested participant decisions individually and as part of a group. (4) June 2017
  • Explain two variables that Philippa may have needed to control when designing her word lists. (4) October 2018
  • Explain two improvements Nairi and Talia could make to their memory experiment. (4) January 2019
  • Explain, using individual differences, two reasons why the students did, or did not, attend the meeting. (4) January 2020