Research issues

• Extraneous variables


  Any variable that could affect the DV
• Situational variables

  Features of experimental situation that could affect the DV
• Participant variables

  Individual differences between participants, could affect DV
• Confounding variables

  Variables researcher failed to control
• Demand characteristics

  Any cue from researcher that could reveal purpose of study to participants
• Investigator effects


  Effect of investigators behaviour on outcome
• Randomisation

  use of chance to reduce researchers influence
• Standardisation

  use of exact same procedures and instructions for all participants