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“Preserving Internal Validity in Correctional Evaluation Research: The Biased Assignment Design as an Alternative to Randomized Design”

Minor, Kevin I.
June 4, 2015

Source: (1990) Journal of Contemporary Criminal Justice. 6: 216-225.

Internal validity refers to the confidence with which
changes in a dependent variable can be isolated from the
effects of extraneous factors and causally attributed to the
effects of an independent variable. While a randomized
design is commonly recommended as the best way to
preserve internal validity, random assignment of subjects
to groups is not always feasible in evaluations of correctional
programs. This paper argues that the biased assignment
design, whereby subjects are assigned to groups
according to controlled criteria, is a viable alternative
means of preserving internal validity which should be
employed more frequently by corrections researchers.
The steps for using the biased assignment design are
presented, as is a strategy for proper data analysis.


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