types of experiments

• Experiments allow us to study cause and effect (causation). They have an IV, and DV and attempt to control other extraneous variables.

  4 types of experiment:

  • Laboratory experiments
  • Field experiments
  • Natural experiments
  • Quasi experiments
• Laboratory experiments are conducted under controlled conditions in which the researcher changes the IV to see the effect on the DV.
• Field experiments are carried out in a natural setting, in which the researcher manipulates the IV to see the effect on the DV
• Natural experiments are where the change in the IV is not bought about by the researcher but would have happened even if the researcher wasn’t there.
• Quasi experiments are where people are compared on an existing difference (IV) that simply exists (has not been determined by anyone) e.g. age or gender
• lab experiments -

  strengths

  • High level of control over the environment and extraneous variables – increases validity
  • Easy to replicate and check results

  limitations

  • Lacks ecological validity – due to researcher control, findings can’t be easily generalised to real life
• field experiments -

  strengths

  • There is some degree of control but in a natural environment so have good internal and external validity

  limitations

  • Less control than lab experimenters so extraneous variables are more likely to distort data, lowering internal validity
• natural experiments -

  strengths

  • Provide opportunity to research things which may not be practical/ ethical if they hadn’t occurred naturally

  limitations

  • A naturally occurring event may happen rarely, reducing research opportunities.
  • You may not be able to randomly allocate pps to conditions
• quasi experiments -

  strengths

  • Often carried our under controlled conditions so have high internal validity

  limitations

  • Cannot randomly allocate pps to conditions so there may be confounding variables