Scientific processes (Experimental design) Flashcards
Experimental design
The different ways in which the testing of participants can be organised in relation to the experimental conditions
Independent groups design
Participants are allocated to different groups where each group represents one experimental condition
Independent groups example:
- One group of participants (group 1) drinking the energy drink (condition A- the experimental condition)
- A different group of participants (group 2) drinking the water (condition B- the control condition)
- These groups would then be compared of the mean of the number of words spoken in a period of 5 mins
Repeated measures
All participants take part in all conditions of the experiment
Matched Pairs
Pairs of the participants are first matched on some variables that may affect the DV. Then one member of the pair is assigned to condition A and the other to condition B
Random allocation
An attempt to control for participants variables in an independent groups design which ensures that each participant has the same chance of being in one condition as any other
Counterbalancing
An attempt to control for the effects of order in a repeated measures design: half the participants experience the conditions in one order and the other half in the opposite order
Strength of repeated measures
- Fewer participants are required; less costly + time consuming
Weakness of repeated measures
- Issues with order effects such as practise effects or fatigue as they take part in both conditions
Strengths of independent groups
- Avoids order effects and reduces demand characteristics making the results more valid
Weaknesses of independent groups
- More participants are required and participant variables may affect the results
Strength of matched pairs
- Avoids order effects and reduces participant variables and demand for characteristics making results more valid
Weakness of matched pairs
- Impossible to match people exactly; unless using identical twins
- More participants are required
