Units of Analysis and the Individual Differences Fallacy in Environmental Assessment

Abstract

The "Ecological Fallacy" is the error of interpreting results based on ecological entities, such as environmental settings, as though the results apply to individuals. This article argues that it is equally erroneous to interpret results based on individuals as though the results apply to settings, and suggests this error be labelled the "Individual Differences Fallacy." Hypothetical data were used to illustrate two conditions for an instrument intended to assess the characteristics of classroom environments. In the first condition, the instrument actually measured differences among individuals; in the second condition, it achieved its goal of measuring differences among settings. When individuals were the units of analysis, results either were inconclusive or incorrectly suggested that the measure of individual differences was superior. Correct and interpretable results were obtained only when environmental settings were the units of analysis. Therefore, future research on environmental assessment should use settings as the primary units of analysis.