#### PSYCH 310 - EXAM 2 - CHAPTER 11

Articulate how a crossed factorial design works

There are two or more independent variables
Researchers cross the two independent variables; they study each possible combination of the IV
Example: Effect of driving while on the phone depended on driver's age
2 x 2 (two levels of one IV) = 4 (cells in d

Explain two reasons to conduct a factorial study

Can test limits
Allows to test whether an independent variable affects different kinds of people, or people in different situations, in the same way
Form of external validity
When researchers test an IV in more than one group at once, they are testing whe

Review studies with one independent variable, which show a simple "difference

pg 312 - Spaghetti box and serving size given experiment. One IV and one DV. No matter what the product, when same amount is in a large container, people use more of the product than when it is in the small container

Describe an interaction as a "difference in differences

The effect of one IV depends on the level of the other IV (pg 314) When people eat icecream they like their food cold more than hot, when people eat pancakes they like their food hot more than cold. You like ice cream cold more than you like hot (cold min

Describe interactions in terms of "it depends

Interaction of two IV - whether the effect of the original IV (cell phone use) depends on another IV (driver age).
Example: Does the effect of cell phones depend on age?

Estimate marginal means in a factorial design to look at main effects

...

Main effect

The overall effect of one IV on the DV, averaging over the levels of the other independent variable. The main effect is a simple difference.
In a factorial design with 2 IV, there are 2 main effects

Marginal means

The means for each level of an IV, averaging over levels of the other IV.

Identify interaction effects two ways: in a table and in a graph

See book pg 321

Given a factorial notion (e.g. 2 x 2), identify the number of IVs, the number of levels of each variable, the number of cells in design, and number of main effects and interactions that will be relevant

Within-groups factorial design; 2 IVs, each with 2 levels, creating four conditions.

Explain the basic logic of three-way factorial designs

Three main effects to test
Each main effect represents a simple, overall difference: the effect of one independent variable, averaged across the other two IVs.
Three possible two-way interactions.
If it is significant, means that the 2-way interaction bet

Determine, from a graph, whether a study shows a three-way interaction

The-two way interactions are different depending on the level of a third IV

Interpret key words that indicate factorial design language in a journal article

If they refer to their study as a 2 x 2 design, a 3 x 2 design, a 2 x 2 x 2 design
Specify design was factorial
"main effect" "interaction" and "significant

Interpret key words in popular press that indicate factorial design.

pg 337
Two IVs
"It depends"
Dependent variable then use phrase "it depends" to identify IV then adds in a second factor
When articles discuss a participant variables (e.g. sex, age, or ethnicity)
Participant variable often moderates another IV