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Chapter 10: Experimental Research - Coggle Diagram
Chapter 10: Experimental Research
Two-Group Experimental Designs
Posttest-Only Control Group Design
No pretest measurements
Covariance Designs
Controls for covariates
Pretest-Posttest Control Group Design
Pretest and posttest measurements
Random assignment
Design notation
Effect
Categories of Experimental Designs
True Experimental Designs: Require random assignment
Quasi-Experimental Designs: No random assignment
Experimental Research Overview
Strength
Internal validity (causality)
Suitable for explanatory research
Definition
Random assignment to treatment levels
Observing effects on dependent variables
Rigorous design involving manipulation of independent variables
Basic Concepts
Treatment Manipulation
Unique feature of experimental research
Requires pretests and pilot tests
Random Selection and Assignment
Random selection: Ensures each unit has a positive chance of being selected
Random assignment: Ensures group equivalence
Treatment and Control Groups
Treatment group(s) receive experimental stimulus
Control group does not
Advanced Experimental Designs
Multifactorial Designs
Multiple factors and levels
Example: 2 x 3 factorial design
Types of Experimental Research
Field Experiments
High internal and external validity
High internal and external validity
Laboratory Experiments
High internal validity
Low external validity
Factorial Designs
Example
Factors: Instructional type (in-class, online) and instructional time (1.5 hrs, 3 hrs)
2 x 2 factorial design
Definition
Manipulation of two or more independent variables
Examines main and interaction effects
Threats to Internal Validity
Testing Threat
Instrumentation Threat
Maturation Threat
Mortality Threat
History Threat
Regression Threat
