Controlling extraneous variables

• Give three ways a researcher can control for extraneous variables.

  • (C)ounterbalancing
  • Random allocation
  • (S)ingle blind
  • (D)ouble blind
  • (R)andomisation
  • (St)andardisation
• What is a demand characteristic?

  Any cue from the researcher or the situation that may be interpreted by participants as revealing the purpose of the investigation.
• What is an investigator effect?

  Any effect of the investigators behaviour (conscious or unconscious) on the dependent variable.
• What can investigator effects include in terms of the investigators behaviour?

  The selection of or interaction with participants during the research process.
• What can investigator effects lead to?

  Participants changing their behaviour within the research situation.
• What can be introduced to overcome investigator effects and demand characteristics?

  Double blind trails
• What can be done to eliminate demand characteristics?

  Single blind or double blind trails
• What can be done to eliminate investigator effects?

  Double blind trail
• What would happen in a drug trail which uses double blind trails.

  Both the participant and the researcher don't know who has the placebo or the real drug.