Experimental Design
Independent groups design participants take part in only one condition.
Repeated measures design all participants take part in all conditions of the experiment
Matched pairs design Participants are matched on important characteristics such as age and IQ and are split up across each condition
Advantages
Advantages
Advantages
Disadvantages
Disadvantages
Disadvantages
Controls the participant variables such as IQ as the participants are matched unlike in an independent group design
There are no order effects as the participants only partake in one condition unlike in a repeated measures design
Can be time consuming to match up participants, so would have to draw participants from a large pool unlike with a repeated measures design
Difficult to completely match participants on important characteristics, so participant variables may still have an effect
There will be no order effects (i.e. participants won't become bored or better at a task if participating in more than one condition)
Can be used when repeated measures design is inappropriate as each condition needs different participants (i.e. a study into gender differences)
Participant variables may affect the dependent variable as there are separate groups of participants for each condition which could lower internal validity
More participants are needed than in a repeated measures design as two separate groups are needed
Participant variables are removed as the participants take part in all conditions increasing the internal validity
Requires fewer participants as they take part in all conditions unlike independent group designs where two separate groups are required
Increased chances of demand characteristics as participants take part in all conditions and may alter their behaviour to help/hinder the study lowering the internal validity
Order effects may occur when participants take part in more than one condition becoming bored or better at the given task reducing internal validity