As a result of the use of random assignment to treatment, randomized experiments typically have high internal validity. However, units are very rarely randomly selected from a well-defined population of interest into an experiment; this results in low external validity. Under nonrandom sampling, this means that the estimate of the sample average…

Introduction: Star and Bowker describe the residual as what does not fit into a category system and as an inevitable byproduct of classification. In this project, we explore what happens when we attempt to give prominence to the residual instead of minimizing it. Methods: The three authors created three "transformations" of a small…