COMPLEX EXPERIMENTAL DESIGNS

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Define a factorial design and why a researcher would use this design

Describe the information provided by main effects and interaction effects in a factorial design

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Describe an IV x PV design Discuss the role of simple main effects in

interpreting interactions Compare the assignment of participants in an

independent groups design, a repeated measures design, and a mixed factorial design

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Provides more information about the relationship than a two level design

Can provide us with a 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

© 2012 The McGraw-Hill Companies, Inc.

© 2012 The McGraw-Hill Companies, Inc.

© 2012 The McGraw-Hill Companies, Inc.

Factorial Designs: Designs with more than one independent variable (or factor)

Simplest Factorial Design 2 x 2 factorial design

Has two independent variables Each independent variable has two levels

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Interpretation of Factorial Designs Main effects of an independent variable Interaction between the independent variables

Factorial Designs with Manipulated and Non-manipulated Variables IV x PV designs

(Independent Variable by Participant Variable)

© 2012 The McGraw-Hill Companies, Inc.

© 2012 The McGraw-Hill Companies, Inc.

Interactions and Moderator Variables Outcomes of a 2 x 2 Factorial Design

1. There may be a significant main effect for independent variable A

2. There may be a significant main effect for independent variable B

3. There may be a significant interaction between the independent variables(See results in following slides)

Interactions and Simple Main Effects Simple main effect of type of questioner Simple main effect of type of question

© 2012 The McGraw-Hill Companies, Inc.

© 2012 The McGraw-Hill Companies, Inc.

© 2012 The McGraw-Hill Companies, Inc.

© 2012 The McGraw-Hill Companies, Inc.

© 2012 The McGraw-Hill Companies, Inc.

© 2012 The McGraw-Hill Companies, Inc.

© 2012 The McGraw-Hill Companies, Inc.

Assignment Procedures and Factorial Designs Independent groups design Repeated measures design Mixed factorial design using combined

assignment

© 2012 The McGraw-Hill Companies, Inc.

© 2012 The McGraw-Hill Companies, Inc.

© 2012 The McGraw-Hill Companies, Inc.

Increasing the Number of Levels of an Independent Variable

Increasing the Number of Independent Variables in a Factorial Design Repeated measures Mixed factorial design using combined

assignment

© 2012 The McGraw-Hill Companies, Inc.