Types of experiment

• What are the types of experiment?

  • Lab
  • Field
  • Natural
  • Quasi
• What is a natural experiment?

  The experimenter cannot manipulate the IV, so the DV is judged as an effect of the IV
• What are the strengths of a natural expeirment?

  • High ecological validity
  • Less demand characteristics
• What are the weaknesses of natural experiments?

  • Can’t randomly allocate participants, so sample bias may be present
  • Ethical issues such as consent
• What is a quasi expeirment?

  Using a naturally occurring IV , such as gender or handedness to measure a DV in a lab
• What is a strength of a quasi experiment?

  Allows comparison of different types of people
• What are the weaknesses of quasi experiments?

  • Can’t change IV so can’t be sure that a change in the DV is due to the IV
  • Can’t randomly allocate participants so there may be biases
• What is a lab experiment?

  Try and eliminate extraneous variables by removing them or keeping them constant in an artificial environment
• What do lab experiments establish?

  Cause and effect
• What are the strengths of lab experiments?

  • High control of extraneous variables, so experiments have high internal validity
  • Results are reliable as conditions can be replicated
• What are the weaknesses with lab experiments?

  • Lacks ecological validity
  • People may alter their behaviour if they know they are being studies (demand characteristics)
  • Experimenter bias may be an issue
• What are field experiments?

  Experiments conducted in real-world settings, manipulating independent variables to observe their effects on dependent variables
• What are the strengths of field experiments?

  • High ecological validity
  • Less demand characteristics
• What are the weaknesses of field experiments?

  • Extraneous variables are less controlled so can become confounding variables
  • Ethical issues such as consent
  • Can’t be precisely replicated so lacks reliability