extraneous variables

• What is counterbalancing?


  In counterbalancing, half the participants take part in condition A and then B. The other half do condition B and then A.
• What does counterbalancing control?

  Order effects
• What is random allocation?

  After the participants have been recruited, they should be randomly assigned to each condition
• What does random allocation control?

  Participant variables
• What is randomisation?


  The use of chance wherever possible
• What does randomisation control for?

  Investigator effects
• What is standardisation?


  Refers to the process in which procedures used in research are kept the same.
• What does standardisation control for?

  Investigator effects and situational variables
• What is single blind?

  Patients do not know which study group they are in.
• What does single blind control for?

  Demand characteristics
• What is double blind?

  Neither the patients nor the researchers know which study group the patients are in.
• What does double blind control for?

  Investigator effects and demand characteristics