Complex Experimental Designs
INCREASING THE NUMBER OF
LEVELS OF AN INDEPENDENT
VARIABLE
Provides more information about the
relationship than a two level design
Curvilinear Relationship
Inverted-U
Comparing Two or More Groups
I.E. How dogs, cats, and birds as opposed to
dogs alone have beneficial effects on nursing
home residents
LINEAR VERSUS POSITIVE
MONOTONIC FUNCTIONS
LINEAR VERSUS POSITIVE
MONOTONIC FUNCTIONS
INCREASING THE NUMBER OF
INDEPENDENT VARIABLES:
FACTORIAL DESIGNS
Factorial Designs: Designs with more than
one independent variable (or factor)
Simplest Factorial Design
2 x 2 factorial design
Has two independent variables
INCREASING THE NUMBER OF
INDEPENDENT VARIABLES:
FACTORIAL DESIGNS
Interpretation of Factorial Designs
Main effects of an independent variable
Interaction between the independent variables
Factorial Designs with Manipulated and
Nonmanipulated Variables
IV x PV designs
(Independent Variable by Participant Variable)
INCREASING THE NUMBER OF
INDEPENDENT VARIABLES:
FACTORIAL DESIGNS


Interactions and Moderator Variables
Outcomes of a 2 x 2 Factorial Design
1.
2.
3.

There may or may not be a significant main effect for
independent variable A
There may or may not be a significant main effect for
independent variable B
There may or may not be a significant interaction between the
independent variables
(See results in next five slides)
Interactions and Simple Main Effects


Simple main effect of anxiety
Simple main effect of studying
INCREASING THE NUMBER OF
VARIABLES: FACTORIAL
DESIGNS
A
INCREASING THE NUMBER OF
VARIABLES: FACTORIAL
DESIGNS
INCREASING THE NUMBER OF
VARIABLES: FACTORIAL
DESIGNS
INCREASING THE NUMBER OF
VARIABLES: FACTORIAL
DESIGNS
INCREASING THE NUMBER OF
VARIABLES: FACTORIAL
DESIGNS
INCREASING THE NUMBER OF
VARIABLES: FACTORIAL
DESIGNS
INCREASING THE NUMBER OF
INDEPENDENT VARIABLES:
FACTORIAL DESIGNS
Assignment Procedures and Factorial
Designs
Independent groups design
Repeated measures design
Mixed factorial design using combined
assignment
INCREASING THE NUMBER OF
INDEPENDENT VARIABLES:
FACTORIAL DESIGNS
INCREASING THE NUMBER OF
INDEPENDENT VARIABLES:
FACTORIAL DESIGNS
INCREASING THE NUMBER OF
INDEPENDENT VARIABLES:
FACTORIAL DESIGNS
INCREASING THE NUMBER OF
INDEPENDENT VARIABLES:
FACTORIAL DESIGNS
Increasing the Number of Levels of an
Independent Variable
2 x 3
Increasing the Number of Independent
Variables in a Factorial Design
2x2x3 = 12 conditions!
Gets unwieldy pretty quickly
INCREASING THE NUMBER
OF VARIABLES: FACTORIAL
DESIGNS