Many people misunderstand and misinterpret conditional probabilities in instances that are highly consequential. This is often true in diagnostic testing where medical professionals will confuse the true positive rate with the actual probability that someone who tests positive really has the disease.

Similar misuse of conditional probability occurs in court trials where a prosecutor will incorrectly use conditional probability to assign a very high chance that the defendant is guilty of crime. This misuse even has a name - it's called the Prosecutor's Fallacy.

This week's discussion topic will be to review and comment on these articles and video about misusing conditional probability which may lead to misdiagnosis of a disease or drug use, or invalid convictions of defendants.

Your comments should reflect your understanding of what you watched and read,

• The Prosecutor's Fallacy Explained (video)Links to an external site.
• Misuse of Statistics in the courtroom: The Sally Clark case (article)Links to an external site.
• Doctors flunk quiz on screening-test math (article)