How Difference Tasks Are Affected by Probability Format, Part 1: A Making Numbers Meaningful Systematic Review

Area of Science:

• Health communication
• Decision science
• Information design

Background:

• The Making Numbers Meaningful project conducted a systematic review to guide health probability data presentation.
• This review focuses on "difference tasks," where individuals evaluate probability variations, such as risk factor impact.

Purpose of the Study:

• To assess the impact of data presentation formats on the communication of health probabilities.
• To evaluate how format influences identification, recall, contrast, categorization, and computation of probability differences.

Main Methods:

• Systematic review of experimental and quasi-experimental studies comparing quantitative health information formats.
• Inclusion of 53 findings from 35 studies across multiple databases and hand searches.
• Extraction of data on stimuli, cognitive tasks, and perceptual, affective, cognitive, or behavioral outcomes.

Main Results:

• Evidence on the effect of format on most difference-level cognitive tasks was weak or insufficient.
• Strong evidence indicates computations with differences are easier using rates per 10^n compared to percentages or "1 in X" rates.
• Adding graphics to numerical data enhances the ease of performing difference-level computations.

Conclusions:

• Few studies were comparable enough to generate robust evidence on probability difference evaluation.
• Rates per 10^n and graphical enhancements are recommended for improving the computation of probability differences in health communication.