Experimental Methods

• What do experimental methods concern?


  The manipulation of an independent variable (IV) to have an effect on the dependent variable (DV) that is measured an stated in results
• What are the different types of experimental methods?


  field, laboratory, quasi, natural
• Describe laboratory design?


  An experiment that takes place in an environment where variables can be carefully controlled
• Describe field design?


  An experiment that is conducted in a more natural environment which variables still be controlled
• Describe a quasi design?


  Experiment where the IV jas not been determined by the researcher, instead it naturally exists e.g in gender difference studies
• Describe a natural design?

  An experiment which the IV is not brought about by the researcher thus nothing would have happened even if the researcher had not been there e.g. in studying reactions to earthquakes
• What are the strengths of a laboratory experiment?


  High degree of control as experimenters control all variables. The IV has been precisely replicated leading to greater accuracy
• What is a strength of a field experiment?


  It is naturalistic- so more natural behaviours hence high ecological validity

  Controlled IV - greater accuracy as IV has been replicated
• What is mean pt by replication?


  Researchers can repeat experiments and check the results
• Give a strength of quasi experiments?


  They have controlled conditions - thus making them more replicable as they are likely to have high internal validity
• Give a strength of natural experiments?


  • It provides opportunities for research that would have otherwise been impossible due to practical/ ethical reasons
  • High external validity- dealing with real life issues
• What are some limitations of a laboratory study?

  Experimenter bias- can affect results, participants may be influenced by these expectations

  Low ecological validity- High degree of control making the situation artificial unlike real life
• What are some limitations of a field experiment?


  Ethical considerations - invasion of privacy and likely to have no informed consent

  Loss of control - Over extraneous variables hence precise replication not possible
• What is a limitation of a quasi experiment?


  Cannot randomly allocate participants to the conditions- so there may be confounding variables presented . Making it harder to conclude that the IV caused the DV.
• What are some limitations of a natural experiment?


  Natural occurring events- Experiments are not likely to be replicable so it is hard to generalise findings

  Difficulty in randomisation- difficult to randomise participants into a group so confounding and extraneous variables become a problem