Textbook - Chapter 9 (Factorial Designs)

what are factorial designs?

experiments that include more than one IV or factor; the most common approach

how are factorial designs set up?

each level of one IV is combined with each level of the others to produce all possible combinations (2×2)

what is the limit of independent variables & levels in a factorial design?

unusual for there to be more than three IVs with more than two or three levels each

why is there a limit of independent variables & levels in a factorial design?

the number of conditions can quickly become unmanageable & the number of participants required to populate all of the conditions can render the design unfeasible (while maintaining the ability to detect a real underlying effect)

what occurs in a between-subjects factorial design?

all of the IVs are manipulated between subjects; each participant would be tested in one condition

what occurs in a within-subjects factorial design?

all of the IVs are manipulated within subjects; each participant is tested for all conditions

what are the advantages to a between-subjects factorial design?

avoids order/carryover effects & minimizes the time & effort of each participant

what are the advantages of a within-subjects factorial design?

more efficient for the researcher & controls extraneous participant variables

what is a mixed factorial design?

to manipulate one IV between subjects & manipulate another within subjects

what is the assignment of participants to conditions or order of conditions?

random (assignment)

what is a non-manipulated independent variable?

a variable that is measured but not manipulated; usually participant variables (self-esteem, gender) & are between-subjects factors

what is needed for a study to be considered an experiment?

at least one manipulated IV; causal conclusions can only be drawn from them

what is a non-experimental study?

contains only non-manipulated IVs

what can factorial experiments be made up of?

manipulated IVs or a combination of manipulated and non-manipulated IVs

how would the results of a factorial experiment be graphed?

one IV in the x-axis, DV in the y-axis, other independent variable uses different colored bars or lines

when are line graphs more appropriate to use?

when representing measurements made over a time interval on the x-axis (times series information)

what are the three kinds of results of interest in a factorial design?

main effects, interaction effects, simple effects

what is a main effect?

the effect of one IV on the DV, averaging across the levels of the other IV; one main effect for each IV; independent of each other

what is an interaction effect?

when the effect of one IV depends on the level of another; primary reserach question is about an interaction

what are the different types of interaction effects?

spreading interactions & cross-over interactions

what are spreading interaction effects?

there is an effect of one IV at one level of the other IV & there is either a weak effect or no effect of that IV at the other level of the other IV

what is a cross-over interaction effect?

one IV has an effect at all levels of the other IV but the effects are in opposite directions

what is implied by an interaction?

the main effects may be misleading; additional (simple effect) analyses must be conducted to determine where that interaction is coming from

what are simple effects analyses?

used to examine the effects of each IV at each level of the other IV; depends on the number of levels of the IV