Factorial designs Flashcards
1
Q
What are factorial designs?
A
- These are when we have more than one variable and we look at how they interact or if they both have an effect.
- It is a closer approximation of real-world settings where independent variables don’t exist alone.
- All levels of each independent variable are combined with all levels of the other independent variables.
- The simplest is a 2x2 factorial design.
2
Q
An example of factorial design
A
- A 2-factor study with 3 levels of one factor and 2 of the other is a 3x2 design.
- Therefore it has 6 conditions
- E.g. test anxiety (high, low, medium) and sex (male, female)
3
Q
What is a condition?
A
A sub-group created when we have different factors
4
Q
What are the two kinds of results you can get in a factorial design?
A
- Main effects
- Interaction effects
5
Q
What are main effects?
A
- Main effects are exclusively due to only one independent variable or another (the effect of one of the IVs on the DV)
- In general, there is one main effect for every independent variable in a study.
- E.g. Word finding (DV) and sleep-deprivation and caffeine-deprivations (factors/IVs). This gives us 4 conditions. So you can look at effect of caffeine or the effect of sleep.
6
Q
What are interaction effects?
A
- When the effects of one IV depends on the level of another IV.
- A statistical interaction occurs when the effect of one independent variable on the dependent variable changes depending on the level of another independent variable.
- E.g. word-finding depends of sleep-deprivation and caffeine-deprivation.
7
Q
How many participants are needed for different designs?
A
Remember that the number of participants needed goes up as your number of conditions increases
- 2x2 between subject: 5 per group, 20 in total
- 2x2 within subjects: 5 per group, 5 in total
- 2x2, mixed design (between and within subjects): 5 per group x2 groups, so 10 in total.
- between subject designs require the highest number of subjects.
