types of experiment

• what is a laboratory experiment?


  refers to a controlled environment whereby standardised procedures are used and participants are allocated to experimental groups

  e.g, Baddeley - encoding of memory
• what is a field experiment?


  manipulation of an independent variable in a real-life setting where the participant sometimes doesn't know the story is taking place

  e.g, Bickman - obedience (uniforms - milkman)
• What is a natural experiment?


  independent variable varies naturally so experimenter does not manipulate it but records effect on dependent variable

  e.g, law that banned smoking - investigators found a change in heart attack rates
• What is a quasi experiment?


  independent variable occurs naturally (e.g, eye colour) so the researcher cannot manipulate and cannot randomly allocate participants to different conditions

  e.g, comparison of gender
• What are the advantages of a laboratory experiment?

  • A high degree of control - variables operationalised for greater accuracy + objectivity
  • Reliable - easily replicable
  • Cause and effect - specific to manipulation of IV
  • Isolation of variables
• What are the disadvantages of a laboratory experiment?

  • Experimenter bias
  • Problems operationalising IV + DV - can become too specific so harder to generalise research
  • Low external (ecological) validity - artificial environment + manipulation
  • Demand characteristics
• What are the advantages of a field/natural/quasi experiment?

  • High ecological validity - representative of the real-world environment and can be generalised to other settings
  • No demand characteristics - participants unaware of the experiment
• What are the disadvantages of a field/natural/quasi experiment?

  • Less control - not as scientifically credible (lack of standardised methods)
  • Replication - decreases reliability
  • Ethics - lack of informed consent
  • Sample bias - participants not randomly allocated