Explaining computation of predictive values: 2 x 2 table versus frequency tree. A randomized controlled trial...

Area of Science:

• Medical Education
• Health Literacy
• Statistical Reasoning

Background:

• Patient involvement in medical decisions requires statistical understanding, yet innumeracy is common, even among physicians.
• The 2x2 table and frequency tree are visual aids used in teaching statistical concepts.
• Physicians and students often lack the statistical thinking skills necessary for informed decision-making.

Purpose of the Study:

• To compare the effectiveness of the 2x2 table versus the frequency tree in teaching predictive value calculations.
• To determine which visual aid better supports statistical thinking for medical decision-making.

Main Methods:

• 184 students without prior statistical training were randomized into two groups: one using a 2x2 table tutorial and the other a frequency tree tutorial.
• Participants completed five predictive value calculations during training and five different calculations in a follow-up session four weeks later.
• The primary outcome measured was the accuracy of the computed predictive values.

Main Results:

• No statistically significant difference was found between the 2x2 table and frequency tree groups in terms of calculation accuracy.
• Approximately 58% of students correctly solved 4-5 tasks immediately after the training session.
• In the follow-up examination, only 26% of students could correctly solve the tasks, regardless of the training method.

Conclusions:

• The study did not support the hypothesis that the 2x2 table is superior to the frequency tree for calculating predictive values.
• Both methods showed similar effectiveness in the short term, but retention of statistical skills was poor.
• Further research is needed to enhance statistical education methods for healthcare professionals and patients.