Two Basic Types of Research Design Methods
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experimental (pre-experimental designs, true experimental designs, quasi-experimental designs, and ex post facto designs); and |
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non-experimental. |
Six characteristics which distinguish experimental research from other methods:
statistical equivalence of subjects in different groups, which is achieved by random assignment of study subjects;
comparison of two or more groups or sets of conditions;
direct manipulation of at least one independent variable;
measurement of each dependent variable;
use of inferential statistics; and
a design that provides maximum control.
Experimental methods deal with the phenomenon of cause and effect.
Internal and External Validity
Internal validity attempts to determine, did the experimental treatments make a difference in this specific study?
External validity attempts to determine, to what populations, settings, treatment variables, and measurement variables can this effect be generalized ?
EXAMPLES OF EXPERIMENTAL RESEARCH DESIGNS
Three Types of Research Designs
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Pre-Experimental |
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Quasi-Experimental |
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True Experimental |
Experimental Notation
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T1 = Pretest |
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T2 = Post-test |
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R = Randomly selected/assigned |
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X = Treatment of subjects (independent variable) |
Pre-Experimental Designs
The difference between Experimental and Pre-experimental designs is pre-experimental designs, lack control of internal validity.
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Research Design with No Control: One-Group Post-test Only Design (X T2) |
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Research Design with Minimal Control: One-Group Pretest/Post-test Design (T1 X T2) |
Quasi-Experimental Designs
Real life situations in leisure research create many instances when experimental research is not possible, but some type of causal inference is needed. The purpose of the quasi-experimental design is to approximate the conditions of the true experiment. Quasi-experimental designs will cause compromises in terms of the internal and external validity of the design. The quasi-experimental research design is characterized by methods of partial control of the study. Otherwise, the steps used in quasi-experimental methods are essentially the same as in true experimental methods.
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A T1 X T2 B T1 T2 |
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T1T2T3 X T4T5T6 | ||
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Group
Pretest Treatment Post
Test Experimental T1 X T Control T1 T2 |
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Baseline Data A - Intervention - Treatment Data B X X X X T1T2T3T4T5T6T7T8T9T10 |
True Experimental Designs
True experimental designs provide the strongest indications for causal effects of the independent variable because of the control and ability to explain or account for extraneous factors.
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Copyright
2001. Northern Arizona University, ALL RIGHTS RESERVED