Experimental methods

• What is an independent groups design?


  • participants are divided into groups
  • one group does an experiment with the first variable
  • the other groups does an experiment with the second variable
  • results are compared
• What is a repeated measures design


  • all participants take part in all variables o the experiment
  • results are compared
• What is a matched pairs design?


  • participants are assigned to groups
  • researchers match participants from both groups based on the characteristics of each member
  • this controls for participant variables
  • the experiment is then conducted as a normal independent groups design
• What is a strength of using a repeated measures design?

  • control for individual differences
  • researcher can be certain the effect is not due to characteristics such as gender or personality
• what is an extraneous variable?

  A variable other than the independent variable that may have an effect on the dependant variable
• Why is it important to control extraneous variables in experimental research?

  • if extraneous variables are not controlled for then result may be confounded
  • the researcher does not know what is causing the effect