This article details the results of a written test designed to reveal how education majors construct and evaluate histograms and frequency polygons. Included is a description of the mistakes made by the students which shows how they tend to confuse histograms with bar diagrams, incorrectly assign data along the Cartesian axes and experience…

This paper presents a new technique in which covariates are controlled and evaluation data still are presented graphically in a manner that makes sense to policy makers. An illustration is provided using data drawn from an evaluation by the author of a major National Science Foundation (NSF) university funding program. (Author)