TYPES OF EXPERIMENT

• Laboratory experiment

  Controlled environment where extraneous and confounding variables can be regulated.

  The IV is manipulated and the effect on the DV is recorded
• strengths of lab experiment

  EVs and CVs can be controlled - the effect of the EVs and Evs on the Dv are minimised. increases internal validity as effect of IV on Dv is clear

  Easily replicated - greater control means less chance that new Evs are introduced.
• weaknesses of lab experiments

  lack generalisability - low external validity as very artificial

  demand characteristics - cues in situation can give away the aims
• Field experiment

  experiment in a natural setting. the Iv is manipulated and the effect on the DV is recorded
• strengths of field experiments

  more natural environment - may make participants more comfortable and behaviour more authentic which increases the generalisability

  Participants unaware of being studied - more likely to behave as they normally would, increases external validity
• weaknesses of field experiments

  more difficult to control CV/EV, changes in the Dv may not be because of IV

  Ethical issues - participants may not have given informed consent
• natural experiment

  experimenter doesn't manipulate IV, changes due to someone or something else.

  DV may be naturally occuring or devised by experimenter
• strengths of a natural experiment

  May be only ethical/practical option - might be unethical to manipulate the IV needed

  Greater external validity - involve real world issues, so findings are more relevant to real experiences
• weaknesses of natural experiments

  event may occur rarely - many natural events are one-off so reduce research opportunity. may limit scope for generalising findings

  participants are not randomly allocated _ experimenter has no control over where participants are placed. results in CVs that aren't controlled
• Quasi Experiments

  IV is based on a pre-existing difference between people. No one has manipulated the variable.

  DV may be naturally occurring
• Strengths of Quasi experiments

  high control - carried out under controlled conditions so replication is possible

  comparisons can be made between people - IV is the difference between people
• Weaknesses of quasi-experiments

  Participants are not randomly allocated - the experimenter has no control over the conditions of the participants. participant variables may have caused change in DV