Description
This book presents some quasi-experimental designs and design features that can be used in many social research settings. The designs serve to probe causal hypotheses about a wide variety of substantive issues in both basic and applied research. Each design is assessed in terms of four types of validity, with special stress on internal validity. Although general conclusions are drawn about the strengths and limitations of each design, emphasis is also placed on the fact that the relevant threats to valid inference are specific to each research setting. Consequently, a threat that is usually associated with a particular design need not invariably be associated with that design.
The first chapter of the book briefly surveys some of the philosophy of science literature on causation. It particularly deals with philosophy of science perspectives that emphasize the relationship between deliberately manipulating objects and perceiving their consequences. These perspectives are then related to the practice and logic of experimentation. We adopt a critical-realist perspective, positing that causal connections are "real" but imperfectly perceived, and we particularly stress epistemological theories that restrict the analysis of causation to the analysis of manipulable causes-factors that can be varied "at will."
The second chapter lists some of the many plausible alternatives that hinder the interpretation of the findings from field research. These alternatives are listed under four headings. Threats to statistical conclusion validity are factors that can lead to invalid conclusions about whether a presumed cause and effect covary. Threats to internal validity are factors that can lead to invalid conclusions about whether a relationship between manipulated or measured variables reflects a causal influence from one of them to the other. Threats to the construct validity of putative causes and effects can lead to invalid conclusions about the construct labels that should be attached to manipulations and measures. Threats to external validity are factors that lead to invalid conclusions about the extent to which results can be generalized across populations, settings and times. Some critiques of this conceptualization of validity are then enumerated and briefly discussed.
ISBN:9780395307908
