How Point (Single-Probability) Tasks Are Affected by Probability Format, Part 1: A Making Numbers Meaningful Systematic Review.

Background. To create guidance on the effect of data presentation format on communication of health numbers, the Making Numbers Meaningful project undertook a systematic review. Purpose. This article (one of a series) covers research studying so-called "point tasks," in which a reader examines stimuli to obtain information about single probabilities. The current article presents the evidence on the effects of data presentation format on multiple outcomes: identification and recall, contrast, categorization, and computation. Data Sources. MEDLINE, Embase, CINAHL, the Cochrane Library, PsycINFO, ERIC, ACM Digital Library; hand search of 4 journals. Finding Selection. Manual pairwise screening to identify experimental and quasi-experimental research comparing 2 or more formats for quantitative health information for patients or other lay audiences. This article reports on 218 findings from 99 articles on single probability communication. Data Extraction. Pairwise extraction of data on stimulus (data in a data presentation format), task, and perceptual/affective/cognitive/behavioral outcomes. Data Synthesis. Most evidence on these outcomes was weak or insufficient. There was moderate to strong evidence that 1) recall was better with icon arrays with human figures than icon arrays with blocks, 2) survival curves make it easier to identify points of highest survival than mortality curves (contrast outcome), 3) adding an average population probability to a message about an individual probability may not affect recall, 4) computation performance is better with bar charts combined with data labels than with either numbers or graphics alone, 5) computation performance with rates is better when denominators match, and 6) framing strongly affects risky choices (contrast). Limitations. Heterogeneous study designs reduced the ability to develop strong evidence. Conclusions. Few findings assessing identification or recall, contrast, categorization, or computation outcomes for point tasks were comparable enough to each other to generate strong evidence.

Highlights: Many researchers have studied the effects of data presentation formats of single probabilities on different outcomes.However, few findings are comparable enough to allow for strong evidence-based conclusions about the impact on identification, recall, contrast, categorization, and computation outcomes.