Experimental Designs

• What is independent groups design?

  There are two different groups of participants who take part in two different conditions
• What is repeated measures design?

  One group of participants takes part in both conditions.
• What is matched pairs design?

  There are two different groups of participants which take part in different conditions but the participants are matched together by qualities.
• Give a strength of Independent groups in terms of order effects.

  Order effects are less likely -> ppts only take part in one condition so don't have the opportunity to repeat the experiment .
• Give a limitation of repeated measures design in terms of order effects.

  Has order effects. -> ppts take part in both conditions so they may improve in their second try. (practice effect)
• Give a strength of matched pairs design in terms of order effects.

  Order effects are less likely -> ppts only take part in one condition so don't have the opportunity to repeat the experiment .
• Give a limitation of independent groups in terms of individual difference

  Doesn't control for individual differences. -> a different ppt takes part in each condition and thus their skills (individual differences) could vary and impact the independent variable.
• Give a strength of repeated measures design in terms of individual differences.

  Controls for individual differences. -> same ppts take part in both conditions allowing for a direct comparison with no individual factors impacting the outcome.
• Give a strength of matched pairs design in terms of individual differences. [3]

  Attempts to control for individual differences. -> matches ppts based on their skills so people that are like each other participate in two different conditions. -> however, ppts can never be matched exactly, there will still be important differences that will effect the dependent variable.
• Give a limitation of independent groups design in terms of how economical it is.

  Less economical than repeated measures. -> requires twice as many ppts for the same experiment.
• Give a strength of repeated measures design in terms of how economical it is.

  More economical than other designs. -> requires half as many ppts for the same experiment.
• Give a limitation of matched pairs design in terms of how economical it is.

  Less economical compared to repeated measures. -> requires twice as many ppts for the same experiment + less time efficient than independant groups as matching participants is time consuming.