Base rate fallacy
Base rate fallacy
The base rate fallacy, also known as base rate neglect or base rate bias, is a cognitive error whereby people tend to ignore the base rate (i.e., general prevalence) information and focus on specific information. This fallacy occurs when the base rate is not adequately considered in the presence of specific information, leading to incorrect conclusions.
Overview[edit | edit source]
The base rate fallacy is a common error in probability and statistics. It occurs when the base rate, or the prior probability of an event, is disregarded in favor of new, specific information. This can lead to significant errors in judgment and decision-making.
For example, consider a medical test for a rare disease. If the disease is very rare (low base rate), even a test with high sensitivity and specificity can produce a high number of false positives. Ignoring the base rate of the disease can lead to overestimating the likelihood that a positive test result indicates the presence of the disease.
Examples[edit | edit source]
Medical Diagnosis[edit | edit source]
In medical diagnosis, the base rate fallacy can lead to misinterpretation of test results. For instance, if a disease has a prevalence of 1 in 1,000, and a test for the disease has a 99% accuracy rate, the probability of having the disease given a positive test result is not 99%. The actual probability is much lower because the base rate of the disease is very low.
Legal Judgments[edit | edit source]
In legal contexts, the base rate fallacy can affect judgments about the likelihood of guilt. For example, if a certain type of evidence is found at a crime scene, jurors might overestimate the probability of the defendant's guilt by focusing on the specific evidence and ignoring the base rate of such evidence being found in the general population.
Related Concepts[edit | edit source]
- Bayesian inference
- Conditional probability
- Cognitive bias
- False positive
- False negative
- Heuristics
- Probability theory
See Also[edit | edit source]
References[edit | edit source]
External Links[edit | edit source]
Search WikiMD
Ad.Tired of being Overweight? Try W8MD's physician weight loss program.
Semaglutide (Ozempic / Wegovy and Tirzepatide (Mounjaro / Zepbound) available.
Advertise on WikiMD
|
WikiMD's Wellness Encyclopedia |
| Let Food Be Thy Medicine Medicine Thy Food - Hippocrates |
Translate this page: - East Asian
中文,
日本,
한국어,
South Asian
हिन्दी,
தமிழ்,
తెలుగు,
Urdu,
ಕನ್ನಡ,
Southeast Asian
Indonesian,
Vietnamese,
Thai,
မြန်မာဘာသာ,
বাংলা
European
español,
Deutsch,
français,
Greek,
português do Brasil,
polski,
română,
русский,
Nederlands,
norsk,
svenska,
suomi,
Italian
Middle Eastern & African
عربى,
Turkish,
Persian,
Hebrew,
Afrikaans,
isiZulu,
Kiswahili,
Other
Bulgarian,
Hungarian,
Czech,
Swedish,
മലയാളം,
मराठी,
ਪੰਜਾਬੀ,
ગુજરાતી,
Portuguese,
Ukrainian
Medical Disclaimer: WikiMD is not a substitute for professional medical advice. The information on WikiMD is provided as an information resource only, may be incorrect, outdated or misleading, and is not to be used or relied on for any diagnostic or treatment purposes. Please consult your health care provider before making any healthcare decisions or for guidance about a specific medical condition. WikiMD expressly disclaims responsibility, and shall have no liability, for any damages, loss, injury, or liability whatsoever suffered as a result of your reliance on the information contained in this site. By visiting this site you agree to the foregoing terms and conditions, which may from time to time be changed or supplemented by WikiMD. If you do not agree to the foregoing terms and conditions, you should not enter or use this site. See full disclaimer.
Credits:Most images are courtesy of Wikimedia commons, and templates Wikipedia, licensed under CC BY SA or similar.
Contributors: Prab R. Tumpati, MD
