Experiments

• laboratory experiment


  conducted in a highly controlled environment, experimenter manipulates IV
• lab experiment strengths


  -high control over extraneous variables = high internal validity

  -replication possible to check results are valid
• lab experiment weaknesses


  -lack of generalisability to beyond the research setting = low ecological validity

  -increase demand characteristics
• field experiment


  IV manipulated in a more natural, everyday setting
• field experiment strengths


  higher ecological validity- behaviour more likely to represent behaviour in real world
• field experiment weaknesses


  -lack of control of extraneous variables = low internal validity

  -replication much harder

  -ethical issues- if ppts. don't know they are being studied they cannot consent/be debriefed
• natural experiment


  change in the IV is not brought about by the researcher, but would have varied naturally, without the researcher
• natural experiment strengths


  -can use this method to conduct research that may not have otherwise been possible due to practical or ethical reasons-

  -high ecological validity
• natural experiment weaknesses


  -can't randomly assign ppts. to groups so hard to control ppt. variables

  -hard to replicate

  -cannot demonstrate casual relationships because IV not directly manipulated
• quasi experiment


  where the IV is not something that varies, but is a condition that exists
• quasi experiment strengths


  -carried out in controlled conditions so have high internal validity

  -replication is possible
• quasi experiment weaknesses


  -cannot randomly allocate ppts. and so could be confounding variables