Perception of quantitative information for treatment decisions

The study was designed to determine which formats for displaying quantities , such as probabilities of treatment risks and benefits, are perceived most accurately and easily by patients. Accuracy and speed of processing were c ompared for six different presentation formats. pie charts, vertical bars, horizontal bars, numbers, systematic ovals, and random ovals. Quantities we re used in two tasks: a choice task that required larger/smaller judgments and an estimate task that required more precise evaluation. The impacts of blue-yellow color and of a treatment-decision context on performance in the two tasks were also investigated. The study included four experiments. Tak en together the results suggest that the formats best for making a choice d iffer from those best for estimating the size of an amount. For making a ch oice, vertical bars, horizontal bars, numbers, and systematic ovals were eq ually well perceived; pie charts and random ovals caused slower and less ac curate performances. For estimating, numbers led to the most accurate estim ates. followed by systematic ovals. The other four formats led to the least accurate estimates. Color and context did not alter which formats were bes t.