Related Experiment Video
Updated: May 15, 2025

An R-Based Landscape Validation of a Competing Risk Model
Published on: September 16, 2022
Risk expression using likelihood ratios and natural frequencies in Bayesian inference tasks-a preregistered
Philipp Schulz1, Odette Wegwarth1,2, Helge Giese3
1Heisenberg Chair for Medical Risk Literacy & Evidence-Based Decisions, Charité - Universitätsmedizin Berlin, Charitéplatz 1, 10117, Berlin, Germany.
Background:
To make reasonable future medical decisions, medical students need to be sufficiently educated to interpret diagnostic tests. Natural frequencies are considered the gold standard for understanding single diagnostic test results. However, they may be less suitable in situations involving sequential diagnostic testing. We test whether odds and likelihood ratios (odds/LR) may serve as a viable alternative in these situations.
Methods:
In our preregistered randomized-controlled crossover trial, we recruited 167 medical students and 162 psychology students. The proportion of correctly calculated positive predictive values of a single (PPV) and two sequential diagnostic tests (sPPV) was the primary, the subjective comprehensibility of the information the secondary outcome.
Results:
The proportion of correct PPVs was significantly higher in the natural frequency (36.2%) compared to the odds/LR format (21.6%), OR 2.41. Conversely, the proportion of correct sPPVs was significantly higher in the odds/LR (10.6%) compared to the natural frequency format (4.9%), OR 2.73. Participants indicated a higher subjective comprehension of test statistics phrased as natural frequencies (Mdn = 19) than as odds/LR (Mdn = -15), r = .61.
Conclusion:
Teaching Odds/LR next to natural frequencies potentially improves medical students' understanding of PPV and may enhance their ability to make future diagnostic decisions.
Trial Registration:
https://doi.org/10.17605/OSF.IO/F3297 .
More Related Videos
Related Concept Videos
Types of Biopharmaceutical Studies: Controlled and Non-Controlled Approaches
Non-controlled studies, commonly employed for initial exploration, lack a control group, rendering them susceptible to biases and external influences. In contrast,...
Odds Ratio
Hazard Ratio
For example, in a clinical trial...
Relative Risk
Randomized Experiments
Simple randomization
Simple...
Crossover Experiments
Crossover designs are performed even with smaller sample sizes since the samples can act as their controls. These are better than simple randomized trials since patients are exposed to all the treatments.

