Chapter 12 Flashcards
interaction effect
whether the effect of the original independent variable depends on the level of another independent variable another way to say it is the difference in differences
spreading interaction
lines arent parallel but they dont cross over each other
when psychological scientists study behavior how many independent and dependent variables do they need to tell the full story
2 independent and 1 dependent
factorial design
two or more independent variables (researchers cross or study each combination of independent variables)
what is a cell
conditions created by an overlay (crossing of independent variables)
what does a 2x2 factorial design mean
2 levels of one independent variables are crossed with two levels of another independent variable
participant variable
a variable whose levels are selected or measured and not manipulated (ex: age, gender, ethnicity)
why do researchers conduct studies with factorial designs
test limits: to test whether an independent variable affects different kinds of people or people in different situations in the same way. (connected to external validity) ex: would cell phone use be impacted by age or the same effect on different ages
Also test theories: are the results of a factorial design consistent with a theory?
in a factorial design with 2 independent variables, how many main and interaction effects will there be?
2 main effects and 1 interaction effect
main effect
the overall effect of one independent variable on the dependent variable
marginal means
the arithmetic means for each level of an independent variable, averaging over levels of the other independent variable
if the sample size is equal in each cell, the marginal means are
a simple average
if the sample size is unequal in each cell, the marginal means are
a weighted average counting the larger sample more
what do marginal means look for
main effects
how do you know if there is an interaction effect
the lines aren’t parallel
independent group factorial design
also known as between-subjects factorial designs. 2x2 there are 4 different groups of participants and different people in each cell
within groups factorial design
also called a repeated measures factorial. Both independent variables are manipulated as within groups. 2x2 there is only one group of participants in all four cells
what kind of design is most efficient
within groups less participants and make more efficient use of participants
what does a 2x3 factorial design mean
two independent variables but one has 2 levels and the other has 3, making 6 cells (the first 2 is 2 levels for the first independent variable and the second 3 is 3 levels of the second independent variable)
mixed factorial design
one independent variable is manipulated as independent groups, and one variable is manipulated as within groups. If the within-group had 12 people and the between-group had 48, the mixed design had 24.
what is a 3 way factorial design
2 x 2 x 2 would create 8 cells or conditions (can be independent groups within or mixed). 3 main effects, 3 two way interactions, and 1 three way interaction
how would you see a three way interaction on a graph
if the two-way interactions are different on both sides, if they are the same, theres no three way interaction
