Graphical depictions of factorial designs

Short Answer Assignment #4

Part 1

PURPOSE: The purpose of this assignment is to help you better understand graphical depictions of factorial designs including main effects and interactions effects.

TASK: Read the following information and prompts and use your textbook and class notes to answer the following questions.

CRITERIA: You will be successful on this assignment if you can: (a) Provide a correct answer to all of the questions using course concepts and descriptions that are clear to another reader.

INFORMATION:

Scientists test whether the Independent Variable influencesthe dependent variable.

Scientists test whether the Dependent Variable depends on the independent variable.

When an experiment has TWO independent variables, the results are broken down:

• Main effect of independent variable #1 on the dependent variable
• Main effect of independent variable #2 on the dependent variable
• Interaction effect of the independent variables on the dependent variable
• When experiments test the effects of two independent variables on a dependent variable, the results are often summarized graphically. In this homework assignment, you will be asked to interpret graphical results of experiments with two independent variables.

Quick guide for getting correct answers on this assignment:

• x-axis = the independent variable #1 (“IV #1”)
• y-axis = dependent variable
• Key (upper-right) = independent variable #2 (“IV #2”)
• Is there a main effect of IV #1?
  • If the average slope of the two lines…
    • … is Flat à no main effect of IV #1
      • e.g., both are flat, or if they cancel each other out by making an “X”
    • … both slope upward or downward = main effect of IV #1
• Is there a main effect of IV #2?
  • If the midpoint of the two lines is equal height à no main effect of IV #2
  • If the midpoint of one of the lines is higher/lower than the other à there is a main effect of IV #2
• Is there an interaction effect?
  • If the lines are parallel, there is NO interaction effect.
  • If the lines are NOT parallel, there is an interaction effect.
• Note: The graphs below represent fabricated data. It’s all made up, just for interpretation practice.

ASSIGNMENT:

For each graph, answer the questions. Explain all effects.

Example:

1. Graph 1
   1. Dependent Variable:

• Independent Variable 1:

• Independent Variable 2:

• Main effect of IV1:

• Main effect of IV2:

• Interaction Effect:

• Graph 2

1. Dependent Variable:

• Independent Variable 1:

• Independent Variable 2:

• Main effect of IV1:

• Main effect of IV2:

• Interaction Effect:

• Graph 3

1. Dependent Variable:

• Independent Variable 1:

• Independent Variable 2:

• Main effect of IV1:

• Main effect of IV2:

• Interaction Effect:

• Graph 4

1. Dependent Variable:

• Independent Variable 1:

• Independent Variable 2:

• Main effect of IV1:

• Main effect of IV2:

• Interaction Effect:

• Graph 5

1. Dependent Variable:

• Independent Variable 1:

• Independent Variable 2:

• Main effect of IV1:

• Main effect of IV2:

• Interaction Effect:

• Graph 6

1. Dependent Variable:

• Independent Variable 1:

• Independent Variable 2:

• Main effect of IV1:

• Main effect of IV2:

• Interaction Effect:

• Graph 7

1. Dependent Variable:

• Independent Variable 1:

• Independent Variable 2:

• Main effect of IV1:

• Main effect of IV2:

• Interaction Effect:

• Graph 8

1. Dependent Variable:

• Independent Variable 1:

• Independent Variable 2:

• Main effect of IV1:

• Main effect of IV2:

• Interaction Effect: