#5 Step 6: Between-Subject Design Flashcards
What is a between-subject design? What must it consist of?
Research by comparing scores from separate groups of individuals/participants.
The design must have
- manipulation,
- control group and
- random assignment.
What is the advantage of between-subject design?
Each group is only measured once, so it is clean and uncontaminated by other treatment factors.
- Practice Effect: progressive improvement in performance as participants gain experience through the series of treatment conditions
- Fatigue Effect: a progressive decline in participant’s performance as they work through a series of treatment conditions
- Contrast Effect: subject’s perception of treatment condition influenced by its contrast with the previous treatment
What is the disadvantage of between-subject design?
Individual differences: each score is obtained from a unique individual who has distinct characteristics from others.
- individual differences can become confounding variables (alt. explanation) but can be solved with random assignment
- can produce high variability in scores, making it difficult to determine whether the treatment really has any effect
Definition of random assignment
random process of assigning participants to conditions
Definition of variability
Variability: a measure of how to spread out a data set is, which measures the size of differences from one score to another
How does variability affect the results?
When research has high within-group variance, it is hard to see the real treatment effect and is considered and error. (aka noise)
The goal is to maximise between-group variance and minimise within-group variance: less noise = easier to conclude that there’s a difference
Ways to effectively minimise within-group variance
- Limit individual differences
- Standardize procedures
- Measure individual differences (ANCOVA)
- Increase sample size
- Use within-subject design
