Chapter 12 (Factorial Experimental Designs)

What is a higher-order factorial design?

They allow us to observe 3 or more factors in the same design.

What is a participant variable?

a quasi-experimental or preexisting variable that is related to personal attributes of a participant

What is an interaction?

a source of variation associated with how the effects of one factor are influenced by, or depend on, the levels of a second factor

What is a main effect?

a source of variation associated with mean differences across levels of a single factor

Why do factorial designs control for threats of internal validity?

by allowing these threats to be factors

Why do factorial designs allow to build on previous research?

by replicating previous result while also demonstrating a new result in the same design

T of F: In order to manipulate the levels of each factor ina factorial design, we must select a sample from at least two or more different populations.

false; select one sample from a single pop.

Which effect, main or interaction, is identified in the cell means of a table summary?

interaction

What will an interaction look like on a graph?

overlap between the two lines (not parallel)

The variance attributed to error in a factorial design is associated with differences in ______ within each cell.

participant scores

Why do factorial designs enhance informativeness?

they allow us to observe the interaction of two or more factors.

When is a factorial experimental design used?

when we manipulate the levels of two or more indep. variables to create groups

A researcher conducts a 3x6 factorial design. How many factors and how many groups?

-3 factors -6 group

A researcher conducts a 4x2 factorial design with 10 participants in each group. How many participants are needed to conduct the experiment for: -a between subjects fact. design -a within subjects fact. design -a mixed fact. design with the first variable being a within-subjects factor -a mixed fact. design with the second variable being a within-subjects factor

-80 -10 -20 -40

What is a complete factorial design? What else is it called?

-A factorial design in which each level of one factor is combined or crossed with each level of the other factor -completely crossed design

What is a two-way factorial design?

-a research design in which participants are observed in groups created by combining or crossing the levels of two factors

Describe a between-subjects factorial design? What three things must researchers do?

-a research design in which the levels of two or more between-subjects factors are combined to create groups, meaning that different participants are observed in each group -manipulate levels of the variable -cross the levels of the two factors -randomly assign

What are the three types of factorial designs?

-between-subjects design -within-subjects design -mixed factorial design

Describe a mixed factorial design? What four things must researchers do?

-different participants are observed at each level of a between-subjects factor and also repeatedly observed across the levels of the within-subjects factor -manipulate -cross -randomly assign -control for order effects

Describe a within-subjects factorial design? What three things must researchers do?

-levels of two or more within-subjects factors are combined to create groups, meaning that the same participants are observed in each group -manipulate -cross -control for order effects

What are three reasons to include two or more factors in an experiment?

-to build on previous research -to control for threats to validity -to enhance the informativeness of interpretation

Using the two-way factorial design, we can identify three sources of variation:

-two main effects (one factor a and one factor b) -one interaction -error variance (due to indiv. diff.)

What is a two-way ANOVA?

-used to analyze the variance in a dependent variable between two groups created by combining the levels of two factors -F=(variance b/w groups)/(variance attrib. to error)

What is a factorial experimental design?

A research design in which groups are created by manipulating the levels of two ore more factors, then the same or different participants are observed in each group using experimental procedures of randomization (for a between-subjects factor) and using control for timing and order effects (within-subjects factor).

What is a factorial design?

A research design in which participants are observed across the combination of levels of two or more factors.