Health Services Research (HSR) Methods
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Nonexperimental Data
Synonyms: Observational Data
Related Terms: Experimental Data; Randomization; Selection Bias; Missing Data; Random Assignment

Information not gathered as part of a controlled experiment or from random assignment of study subjects. Nonexperimental data are commonly used in social science research, particularly when gathering experimental data would be too costly or unethical. Because the researcher cannot control assignment of subjects to the treatment and control groups, nonexperimental data are more difficult than experimental data to analyze and interpret. Examples of nonexperimental data include survey data, administrative records, and standardized test scores. They also are known as observational data.

Further Reading
Kennedy, P. 1998. A Guide to Econometrics, Cambridge, MA: The MIT Press.

Greene, L.. 2003. Econometric Analysis, 5th ed., Upper Saddle River, NJ: Prentice Hall.

Wooldridge, J.M. 2003. Introductory Econometrics, Mason, OH: Thomas South-Western.