Final exam Flashcards
what are the reasons to add a IV
- identify boundary conditions
- identify curvilinearity
- test multiple treatments
identify boundary conditions
- where does it stop mattering (stop having an effect)
identify curvilinearity
- does the effect have an optimal level (works till a certain point and then start going down)
test multiple treatments
- compare
costs of adding levels of an IV
- decreases power and increases the chance of type 2 errors
- you need a larger sample size
- need more resources
factorial designs
experiments with two or more independent variables
participant variables
a variable that is selected/ measures not manipulated
- usually a characteristic of the participant
reasons to add variables to an experiment
- test boundary conditions
- test a theory
factorial designs and boundary conditions
Does an IV affect different kinds of people, or people in different situations, in the same way?
boundary conditions
limits to an effect
- testing the generalizability of a casual variable
- testing moderators
- test of external validity
test a theory
does the study support your theory
costs to adding variables
- decreases power and increases the chance of type 2 errors
- need a large sample size
- need more resources
- complex
factorial designs
- Independent group designs
- Within-groups designs
- Mixed designs
Between groups factorial design
No participant experiences more than one condition (they are in one of the four)
Within groups factorial designs
All participants experience all four conditions
Mixed groups factorial design
- Some participants experience the 2 levels of the one variable and the other participants experience the two levels of the other variable
- benefit less participants and time
main effect
the overall effect of one independent variable on the dependent variable, averaging over the levels of the other independent variable
interaction
when the effect of one independent variable on the dependent variable depends on the level of another independent variable
how do you get the main effect
- add the average score of the two levels of the IV and divide by 2
- marginal mean
how do you get the interaction
Look at the difference between the levels of the independent variable for both the levels of the independent variables
crossover interaction
it depends
spreading interaction
especially
quasi-experiments
less experimental control than a true experiment
- some external factor
quasi-independent variable
Iv that researcher doesn’t have full experimental control over
- act of nature
- government policy
- participants themselves