Chapter 11 - Complex Experimental Designs

Question 1

Describe factorial designs with reference to multiple levels and multiple independent variables

Answer 1

Factorial Design: an experimental study in which two or more independent variables are simultaneously manipulated or observed in order to study their joint influence (interaction effect) and separate influences (main effects) on the dependent variable.

Multiple Levels
Level: the quantity, magnitude, or category of the independent variable being studied.
These are often expressed as different conditions.
There may be two or more levels of an independent variable in a study.

Multiple Independent Variables
Independent Variable: the variable in an experiment that is specifically manipulated or is observed to occur before the dependent variable, in order to assess its effect or influence.
There may be two or more independent variables in a study.

Question 2

Interpret the results of a factorial design using main effects, interactions, and simple main effects

Answer 2

Main Effect: the consistent total effect of a single independent variable on a dependent variable over all other independent variables in an experimental design.

Interaction Effect: in a factorial design, the joint effect of two or more independent variables on a dependent variable above and beyond the sum of their individual effects.

Simple Main Effect: in a factorial design, the effect of one independent variable on the dependent variable, at one particular level of another independent variable.

Question 3

State three considerations for factorial designs