Types of experiment

• Laboratory experiment -

  A controlled environment where extraneous and confounding variables can be regulated. Participants go to the researcher. The IV is manipulated and the effect on the DV is recorded.


  Pros:

  • EVs and CVs can be controlled
  • Can be easily replicated (standardised procedures)

  Cons:

  • may lack generalisability (too much control)
  • demand characteristics can be an issue
• Field experiment -

  A natural setting. The researcher goes to participants. The IV is manipulated and the effect on the DV is recorded.


  Pros:

  • More natural environment
  • Participants are unaware of being studied

  Cons:

  • More difficult to control EVs
  • Ethical issues
• Natural experiment -

  The experimenter does not manipulate the IV. The IV would have varied even if the experimenter wasn't interested. DV may be naturally occurring (e.g. exam results) or may be measured by the experimenter.


  Pros:

  • May be the only ethical option
  • Greater external validity

  Cons:

  • The natural event may only occur rarely
  • Participants are not randomly allocated
• Quasi-experiment -

  IV is based on a pre-existing difference between people, e.g. age or gender. No one has manipulated this variable, it simply exists. DV may be naturally occurring or may be measured by the experimenter.


  Pros:

  • There is often high control
  • Comparisons can be made between people

  Cons:

  • Participants are not randomly allocated
  • Casual relationships are not demonstrated (cannot say for certain the change in the DV is due to the IV)