Using Specialized Research Designs - Lecture Slides | PSYC 330, Study notes of Psychology

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Chapter 11

Using Specialized Research Designs

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The Mixed Design

Includes a between-subjects and a within-subjects factor in the same design

Allows you to evaluate the effects of variables that cannot be manipulated effectively within-subjects

Complex mixed designs include more than two factors, with any combination of between-subjects and within-subjects factors

© 2008 The McGraw-Hill Companies, Inc., All Rights The Nested Design

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Combining Experimental and

Correlational Designs

Including a covariate in an experimental design  (^) A covariate is a correlational variable (e.g., self-esteem) in an experimental design

“Subtracting out” the influence of the covariate reduces error variance  (^) Makes your design more sensitive to the effects of the independent variable

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Quasi-Experimental Designs

Time-Series Design

Make several observations of behavior before and after introducing your independent variable

Interrupted Time-Series Design

Make several observations before and after some naturally occurring event

Equivalent Time Samples Design  (^) Repeatedly introduce the treatment condition, alternated with periods of observation without the treatment

Nonequivalent Control Group Design

Include a time-series component and a control group that is not exposed to the independent variable

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The Pretest-Posttest Design

Pretest administered before exposure to experimental treatment

Unlike quasi-experimental designs, this is a true experimental design

Used to assess the impact of some change on performance

There is a problem with pretest sensitization  (^) Taking the pretest may alter the way a person performs in an experiment

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The Solomon Four-Group

Design

Variation on the pretest-posttest design

Allows you to evaluate the impact of a pretest on posttest performance

Adds two groups to the basic pretest-posttest design

A treatment-posttest group

A posttest-only group

© 2008 The McGraw-Hill Companies, Inc., All Rights The Solomon Four-Group Design

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The Cross-Sectional Design

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The Longitudinal Design  (^) A single group of participants is measured several times over some period of time (e.g., months or years)

Avoids the generation effect that may plague a cross- sectional study

May still have a cross-generational problem  (^) Results from a longitudinal study on one generation may not generalize to another

Problems with the longitudinal design  (^) Subject mortality  (^) Multiple observation effects

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The Cohort-Sequential Design  (^) Combines a cross-sectional and longitudinal component in the same design

Allows you to test for, but not eliminate, generation effects

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The Cohort-Sequential Design