Effects of Numerical Versus Foreground-Only Icon Displays on Understanding of Risk Magnitudes

Using Icon Arrays to Communicate Gambling Information Reduces the Appeal of Scratch Card Games

Past work has demonstrated that presenting statistical information in a foreground-background icon array can improve risk understanding, reduce decision-making biases, and decrease the salience of low-probability risks. In the present study, we assess whether presenting readily available gambling information within a foreground-background icon array influences individuals' gambling-related judgments (e.g., their perceived likelihood of winning a prize). Across two experiments (N = 1151), we find that using icon arrays to present gambling information reduces the appeal of scratch card games. That is, participants presented with gambling information in a foreground-background icon array, as opposed to a non-graphical numerical format, reported feeling less likely to win a prize, less excitement to play, and less urge to gamble on a scratch card game presented in a hypothetical gambling task. Overall, we conclude that presenting gambling information in an icon array format represents a simple yet promising tool for correcting gamblers' often overly-optimistic perceptions and reducing the appeal of negative expected value scratch card games.

Effects of icon arrays to communicate risk in a repeated risky decision-making task

In two experiments, participants decided on each of several trials whether or not to take a risk. If they chose to take the risk, they had a relatively high probability (from 75% to 95%) of winning a small number of points and a relatively low probability (5% to 25%) of losing a large number of points. The loss amounts varied so that the expected value of taking the risk was positive on some trials, zero on others, and negative on the rest. The main independent variable was whether the probability of losing was communicated using numerical percentages or icon arrays. Both experiments included random icon arrays, in which the icons representing losses were randomly distributed throughout the array. Experiment 2 also included grouped icon arrays, in which the icons representing losses were grouped at the bottom of the array. Neither type of icon array led to better performance in the task. However, the random icon arrays led to less risk taking than the numerical percentages or the grouped icon arrays, especially at the higher loss probabilities. In a third experiment, participants made direct judgments of the percentages and probabilities represented by the icon arrays from Experiment 2. The results supported the idea that random arrays lead to less risk taking because they are perceived to represent greater loss probabilities. These results have several implications for the study of icon arrays and their use in risk communication.

Reactions to geographic data visualization of infectious disease outbreaks: an experiment on the effectiveness of data presentation format and past occurrence information

OBJECTIVES

This study intended to compare the effectiveness of thematic maps with that of tabular data in comprehension and memory of risk magnitudes, with Zika virus (ZIKV) disease outbreaks in the United States as the subject matter. The study also aimed to examine the effects of data presentation format and past occurrence information on risk perception and risk avoidance intention.

STUDY DESIGN

This study used an experiment.

METHODS

Each participant was randomly assigned to view ZIKV disease 2017 incidence data presented in one of the three formats: a choropleth map, a graduated-circle map, and a table, after which they answered questions about comprehension and memory of risk magnitudes. Each participant was then randomly assigned to view or not to view incidence data of the previous occurrence of ZIKV outbreaks in 2016, after which they answered questions about risk perception and risk avoidance intention.

RESULTS

The results revealed the effectiveness of thematic maps over tabular data in comprehension, risk perception, and risk avoidance intention. Compared to tabular data, the choropleth map led to a better comprehension of relative risk magnitudes, the graduated-circle map led to higher risk perception, and both thematic maps led to greater risk avoidance intention. In contrast, tabular data led to better recognition of absolute risk magnitudes than both thematic maps. In addition, past occurrence information enhanced risk perception and risk avoidance intention.

CONCLUSIONS

The findings reveal the importance of data presentation format in comprehension and memory of risk magnitudes. This can be attributed to the cognitive match between the information emphasized in the presentation and that required by the tasks. The findings also suggest that data presentation format and past occurrence information are important judgmental heuristics that help to form risk perception and risk avoidance intention.

Performance feedback on the quality of care in hospitals performing thrombectomy for ischemic stroke (PERFEQTOS): protocol of a stepped wedge cluster randomized trial

Background

Although the provision of performance feedback to healthcare professionals based on data from quality registries is common practice in many fields of medicine, observational studies of its effect on the quality of care have shown mixed results. The objective of this study is to evaluate the effect of performance feedback on the quality of care for acute ischemic stroke.

Methods

PERFEQTOS is a stepped wedge cluster randomized trial in 13 hospitals in the Netherlands providing endovascular thrombectomy for ischemic stroke. The primary outcome is the hospital’s door-to-groin time. The study starts with a 6-month period in which none of the hospitals receives the performance feedback intervention. Subsequently, every 6 months, three or four hospitals are randomized to cross over from the control to the intervention conditions, until all hospitals receive the feedback intervention. The feedback intervention consists of a dashboard with quarterly reports on patient characteristics, structure, process, and outcome indicators related to patients with ischemic stroke treated with endovascular thrombectomy. Hospitals can compare their present performance with their own performance in the past and with other hospitals. The performance feedback is provided to local quality improvement teams in each hospital, who define their own targets on specific indicators and develop performance improvement plans. The impact of the performance feedback and improvement plans will be evaluated by comparing the primary outcome before and after the intervention.

Discussion

This study will provide evidence on the effectiveness of performance feedback to healthcare providers. The results will be actively disseminated through peer-reviewed journals, conference presentations, and various stakeholder engagement activities.

Trial registration

Netherlands Trial Register NL9090. Registered on December 3, 2020

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05819-z.

The communication of uncertainty in health: A scoping review

OBJECTIVE

To conduct a scoping review of existing studies that examine communication strategies that address uncertainty in health and categorize them using the taxonomy of uncertainty.

METHODS

Relevant articles retrieved from ten databases were categorized according to the dimensions of the taxonomy of uncertainty, and study characteristics were extracted from each article.

RESULTS

All articles (n = 63) explored uncertainty in the context of probabilistic risk and related to scientific issues (n = 63; 100%). The majority focused on complexity (n = 24; 38.1%) and uncertainty experienced by patients (n = 52; 82.5%). Most utilized quantitative methods (n = 46; 73.0%), hypothetical scenarios (n = 49; 77.8%), and focused on cancer (n = 20; 31.7%). Theory guided messages and study design in fewer than half (n = 27; 42.9%).

CONCLUSIONS

Heterogeneity in terminology used to refer to different types of uncertainties preclude a unified research agenda on uncertainty communication. Research predominately focuses on probability as the source of uncertainty, uncertainties related to scientific issues, and uncertainty experienced by patients.

PRACTICE IMPLICATIONS

Additional efforts are needed to understand providers' experience of uncertainty, and to identify strategies to address ambiguity. Future studies should use consistent terminology to allow for coherence and advancement of uncertainty communication scholarship. Continued efforts to refine the existing taxonomy should be undertaken.

Current Challenges When Using Numbers in Patient Decision Aids: Advanced Concepts

BACKGROUND

Decision aid developers have to convey complex task-specific numeric information in a way that minimizes bias and promotes understanding of the options available within a particular decision. Whereas our companion paper summarizes fundamental issues, this article focuses on more complex, task-specific aspects of presenting numeric information in patient decision aids.

METHODS

As part of the International Patient Decision Aids Standards third evidence update, we gathered an expert panel of 9 international experts who revised and expanded the topics covered in the 2013 review working in groups of 2 to 3 to update the evidence, based on their expertise and targeted searches of the literature. The full panel then reviewed and provided additional revisions, reaching consensus on the final version.

RESULTS

Five of the 10 topics addressed more complex task-specific issues. We found strong evidence for using independent event rates and/or incremental absolute risk differences for the effect size of test and screening outcomes. Simple visual formats can help to reduce common judgment biases and enhance comprehension but can be misleading if not well designed. Graph literacy can moderate the effectiveness of visual formats and hence should be considered in tool design. There is less evidence supporting the inclusion of personalized and interactive risk estimates.

DISCUSSION

More complex numeric information. such as the size of the benefits and harms for decision options, can be better understood by using incremental absolute risk differences alongside well-designed visual formats that consider the graph literacy of the intended audience. More research is needed into when and how to use personalized and/or interactive risk estimates because their complexity and accessibility may affect their feasibility in clinical practice.

Probability Size Matters: The Effect of Foreground-Only versus Foreground+Background Graphs on Risk Aversion Diminishes with Larger Probabilities

Graphs are increasingly recommended for improving decision-making and promoting risk-avoidant behaviors. Graphs that depict only the number of people affected by a risk ("foreground-only" displays) tend to increase perceived risk and risk aversion (e.g., willingness to get vaccinated), as compared to graphs that also depict the number of people at risk for harm ("foreground+background" displays). However, previous research examining these "foreground-only effects" has focused on relatively low-probability risks (<10%), limiting generalizability to communications about larger risks. In two experiments, we systematically investigated the moderating role of probability size on foreground-only effects, using a wide range of probability sizes (from 0.1% to 40%). Additionally, we examined the moderating role of the size of the risk reduction, that is, the extent to which a protective behavior reduces the risk. Across both experiments, foreground-only effects on perceived risk and risk aversion were weaker for larger probabilities. Experiment 2 also revealed that foreground-only effects were weaker for smaller risk reductions, while foreground-only displays decreased understanding of absolute risk magnitudes independently of probability size. These findings suggest that the greater effectiveness of foreground-only versus foreground+background displays for increasing perceived risk and risk aversion diminishes with larger probability sizes and smaller risk reductions. Moreover, if the goal is to promote understanding of absolute risk magnitudes, foreground+background displays should be used rather than foreground-only displays regardless of probability size. Our findings also help to refine and extend existing theoretical accounts of foreground-only effects to situations involving a wide range of probability sizes.

When Does the Incremental Risk Format Aid Informed Medical Decisions? The Role of Learning, Feedback, and Number of Treatment Options

Background. Informed medical decisions require understanding the benefits and risks of treatments. This entails comparing treatment outcomes to a control group. The incremental risk format has been recommended as it directly visualizes the differences between treatment and control group in 1 graph, whereas they have to be calculated from 2 separate graphs in the total risk format. We investigated when the incremental risk format aids understanding. Methods. In 2 experiments, participants received information about medical treatments, either as incremental or total risk format. We assessed verbatim knowledge (precise quantitative knowledge), gist knowledge (knowledge of essential meaning), and evaluations of the formats. Study 1 (N = 99) consisted of only 1 trial with medical information and also assessed recall. Study 2 (N = 222) assessed learning across multiple trials and also varied the presence of feedback and the number of treatment options. Results. In study 1, the incremental risk format (v. total risk format) led to worse knowledge, recall, and evaluations. In study 2, participants learned to understand the incremental risk format over time, resulting in comparable verbatim knowledge and evaluations as in the total risk format, as well as in even better gist knowledge. Feedback and number of treatment options did not moderate the effect of risk format. Limitations. The studies were conducted with nonpatient samples, and study 2 employed hypothetical treatments. Conclusions. The incremental risk format was initially less understandable than the total risk format. After a short learning period, however, the incremental risk format resulted in better gist knowledge and was comparable otherwise, which suggests that participants had to get used to that format. This has important implications for the study of new formats.

Designing Graphs that Promote Both Risk Understanding and Behavior Change

Graphs show promise for improving communications about different types of risks, including health risks, financial risks, and climate risks. However, graph designs that are effective at meeting one important risk communication goal (promoting risk-avoidant behaviors) can at the same time compromise another key goal (improving risk understanding). We developed and tested simple bar graphs aimed at accomplishing these two goals simultaneously. We manipulated two design features in graphs, namely, whether graphs depicted the number of people affected by a risk and those at risk of harm ("foreground+background") versus only those affected ("foreground-only"), and the presence versus absence of simple numerical labels above bars. Foreground-only displays were associated with larger risk perceptions and risk-avoidant behavior (i.e., willingness to take a drug for heart attack prevention) than foreground+background displays, regardless of the presence of labels. Foreground-only graphs also hindered risk understanding when labels were not present. However, the presence of labels significantly improved understanding, eliminating the detrimental effect of foreground-only displays. Labels also led to more positive user evaluations of the graphs, but did not affect risk-avoidant behavior. Using process modeling we identified mediators (risk perceptions, understanding, user evaluations) that explained the effect of display type on risk-avoidant behavior. Our findings contribute new evidence to the graph design literature: unlike what was previously feared, we demonstrate that it is possible to design foreground-only graphs that promote intentions for behavior change without a detrimental effect on risk understanding. Implications for the design of graphical risk communications and decision support are discussed.

Information visualisation as a resource for popularising the technical-biomedical aspects of the last Ebola virus epidemic: The case of the Spanish reference press

This study explores the role that information visualisation played in the popularisation of the technical-biomedical aspects of the last Ebola virus epidemic, the most devastating to date. Applying content analysis methods, the total population of information visualisations ( N = 209) was coded and analysed to identify topics, and to define features and identify patterns in the images. The corpus was based on the record of articles with graphics appearing in five Spanish reference newspapers from 22 March 2014 to 13 January 2016, the start and suppression of the epidemic, respectively. The results suggest that information visualisation was a key factor in the popularisation of the epidemic's technical-biomedical aspects, as well as contributing actively to construct, in the words of Myers, a narrative of nature.

Biasing and debiasing health decisions with bar graphs: Costs and benefits of graph literacy

Bar graphs can improve risk communication in medicine and health. Unfortunately, recent research has revealed that bar graphs are associated with a robust bias that can lead to systematic judgement and decision-making errors. When people view bar graphs representing means, they tend to believe that data points located within bars are more likely to be part of the underlying distributions than equidistant points outside bars. In three experiments, we investigated potential consequences, key cognitive mechanisms, and generalisability of the within-the-bar bias in the medical domain. We also investigated the effectiveness of different interventions to reduce the effect of this bias and protect people from errors. Results revealed that the within-the-bar bias systematically affected participants’ judgements and decisions concerning treatments for controlling blood glucose, as well as their interpretations of ecological graphs designed to guide health policy decisions. Interestingly, individuals with higher graph literacy showed the largest biases. However, the use of dot plots to replace bars improved the accuracy of interpretations. Perceptual mechanisms underlying the within-the-bar bias and prescriptive implications for graph design are discussed.

Designing Visual Aids That Promote Risk Literacy: A Systematic Review of Health Research and Evidence-Based Design Heuristics

Background Effective risk communication is essential for informed decision making. Unfortunately, many people struggle to understand typical risk communications because they lack essential decision-making skills. Objective The aim of this study was to review the literature on the effect of numeracy on risk literacy, decision making, and health outcomes, and to evaluate the benefits of visual aids in risk communication. Method We present a conceptual framework describing the influence of numeracy on risk literacy, decision making, and health outcomes, followed by a systematic review of the benefits of visual aids in risk communication for people with different levels of numeracy and graph literacy. The systematic review covers scientific research published between January 1995 and April 2016, drawn from the following databases: Web of Science, PubMed, PsycINFO, ERIC, Medline, and Google Scholar. Inclusion criteria were investigation of the effect of numeracy and/or graph literacy, and investigation of the effect of visual aids or comparison of their effect with that of numerical information. Thirty-six publications met the criteria, providing data on 27,885 diverse participants from 60 countries. Results Transparent visual aids robustly improved risk understanding in diverse individuals by encouraging thorough deliberation, enhancing cognitive self-assessment, and reducing conceptual biases in memory. Improvements in risk understanding consistently produced beneficial changes in attitudes, behavioral intentions, trust, and healthy behaviors. Visual aids were found to be particularly beneficial for vulnerable and less skilled individuals. Conclusion Well-designed visual aids tend to be highly effective tools for improving informed decision making among diverse decision makers. We identify five categories of practical, evidence-based guidelines for heuristic evaluation and design of effective visual aids.

Designing Graphs to Communicate Risks: Understanding How the Choice of Graphical Format Influences Decision Making

Previous research suggests that the choice of graphical format for communicating risk information affects both understanding of the risk magnitude and the likelihood of acting to decrease risk. However, the mechanisms through which these effects work are poorly understood. To explore these mechanisms using a real-world scenario, we examined the relative impact of two graphical displays for depicting the risk of exposure to unexploded ammunition during potential land redevelopment. One display depicted only the foreground information graphically (a bar graph of the number of people harmed), and a second depicted the foreground and background graphically (a stacked bar graph representing both the number harmed and at risk). We presented 296 participants with either the foreground-only or the foreground and background graphical display and measured a broad set of outcome variables, examining (1) the graphical display effect on each of the outcome measures and (2) the pathways by which any display effects work to influence decision making. We found that the foreground-only graphical display increased perceived likelihood and experienced fear, which produced greater worry, which in turn increased risk aversion. In addition, a positive evaluation of the communication materials increased support for policies related to land redevelopment, whether those policies were risk taking or risk mitigating. Finally, the foreground-only graphical display decreased understanding of the risk magnitude, showing that approaches to accomplish one risk communication goal (promoting risk-averse decisions) may do so at the expense of another goal (increasing understanding).