Independent measures design

• Independent Measures Design

  Using DIFFERENT participants in each condition of the experiment.
• Data


  Data for each level of IV is independent because it is not related to other data.
• Advantage of this design

  Participants encounter experimental setting only once; unlikely to notice/respond to demand characteristics.
• Demand characteristics

  Features of the experimental situation which give away the aim and can cause participants to try and alter behaviour to match their beliefs of what is supposed to happen; reduces validity of study.
• Disadvantage of this design

  Individual differences between participants that could influence findings, can be solved with random allocation.
• Random allocation

  Reduce the effect of confounding variables; participants are put in each level of the IV so each person has an equal chance of being in any condition.
• Order effects; Strength

  Different participants used in each level of IV; no order effects.
• Demand characteristics; Strength

  Participants see only one level of IV; no demand characteristics.
• Random Allocation; Strength

  Reduces effects of individual differences.
• Participant Variables; Weakness

  Can distort result if there are important individual differences between participants in different levels of IV.
• Sample size; Weakness

  More participants needed; study may be less ethical if participants are harmed and less effective if there is a small sample because participants are hard to find.