Related Experiment Video
Updated: May 7, 2026

Setting Up a Stroke Team Algorithm and Conducting Simulation-based Training in the Emergency Department - A Practical Guide
Published on: January 15, 2017
Using tree diagrams without numerical values in addition to relative numbers improves students' numeracy skills: a
Hendrik Friederichs1, Sandra Ligges2, Anne Weissenstein1
1University of Muenster, Studienhospital, Muenster, Germany (HF, AW).
Background:
Physicians and medical students may lack sufficient numeracy skills to make treatment decisions, interpret test results, and practice evidence-based medicine. We evaluated whether the use of a tree diagram without numerical values as an aid for numerical processing might improve students' test results when dealing with percentages.
Methods:
A prospective randomized study was carried out with 102 third-year students. Participants received 3 diagnostic test problems and were asked to determine positive predictive values. The information in these tests was expressed either in (1) natural frequencies, (2) conditional probabilities, or (3) conditional probabilities with a tree diagram without numbers.
Results:
Ninety-eight (96.1%) complete data sets could be obtained. The group working with natural frequencies achieved significantly higher test results (n = 29, mean score: 1.1, P = 0.045) than the group working with conditional probabilities (n = 34, mean score: 0.56). The students who were given a tree diagram in addition to conditional probabilities (n = 35, mean score: 1.26) also achieved significantly better scores than the group with conditional probabilities alone (P = 0.008). The difference between the group who had received natural frequencies and the group working with conditional probabilities and the tree diagram was not significant.
Conclusions:
We suggest the use of a tree diagram as a visual aid when dealing with diagnostic tests expressed in conditional probabilities.
Related Concept Videos
Numerical Calculations
The solution to a problem is obtained using different methods. While manually solving algebraic symbols is one of the most common methods, the graphical method is often preferred. Computers...
Real Number Operations
How Data are Classified: Numerical Data
Quantitative data may be either discrete or continuous. All quantitative data that take on only specific numerical...
Bar Graph
Multiple Bar Graph
Each bar or column in the multiple bar graph represents a data value. These graphs are used primarily in interrelating two or more sets of data. The categories of different kinds of data are listed along the horizontal or x-axis, whereas...
Survival Tree
Ā Building a Survival Tree
Constructing a survival tree begins...
