Experimental design is a way of allocating participants to conditions in an experiment. Most experiments have two conditions; e.g. whether participants perform better under noisy or quiet conditions.
Repeated Measures Design - experimental design in which participants take part in each condition. Advantages:
- Researchers are comparing the same participants; any changes are real changes and not due to the participant changing.
- More practical; do not need to use as many participants as with independent groups.
- Order effects; participants may underperform because they are tired or bored.
- Practice effect; they have done the experiment once already.
Independent Measures Design - experimental design in which participants are different in each condition.
- Get rid of the order effects; different participants, different conditions.
- Different participants in different conditions; differences could be down to the individual.