L7: Experimental Designs Flashcards
What is Experimental Design?
How Participants are assigned to different conditions
What are the three main types of experimental designs?
- Independent groups
- Repeated measures
- Matched pairs
What are Independent Groups?
- Different ppts used in each condition
- Each group of ppts is independent from one another
- Ppts are randomly allocated to each condition to balance any participant variables
Advantages of Independent Groups
- No Order effects as there are different ppts in each condition
- Demand characteristics are reduced. One condition = less chance to guess purpose of study
- Saves time, both conditions can be tested together
Disadvantages of Independent Groups
- More ppts required
- Different results could be due to participant variables rather than changing the IV
What is the Repeated Measures Experiment?
Each ppt is tested in all conditions
Advantages of Repeated Measures
- No participant variables
- Less people required (compared to independent groups)
Disadvantages of Repeated Measures
- Demand Characteristics likely as ppt are involved with entire study
- Time consuming esp if time gap is necessary
- Order effects
How to Challenge Order Effects
Counterbalancing
- half of the ppt do Condition A and other half do Condition B
- Swap after
- Does NOT eliminate Order Effects because each ppt still has to do two tasks, but controls the impact of them and allows it to be evenly distributed
What is the Matched Pairs Experiment?
- Diff ppt used in all conditions (like Independent Groups)
- Ppts in the 2 groups are matched on characteristics needed for the study e.g intelligence, gender, age
Advantages of Matched Pairs
- Less risk of Order Effects
- Less demand characteristics
- Participant Variables are unlikely as groups are matched
Disadvantages of Matched Pairs
- 2x ppt needed
- Matching process is hard to do accurately
- Matching process is time consuming
