A mis-statement of a probability as a result of a misunderstanding of conditional probability. (See also defender's fallacy.) As an example, suppose a blood type possessed by only 1% of the population is found at a crime scene. The accused has blood of this type. The prosecutor argues that there is only a 1% chance that the accused would have blood of this type (event A, say) if innocent (event B, say) and concludes that the accused is guilty. The prosecutor has quoted P(A|B) when it is P(B|A) that is relevant.
Subjects: Probability and Statistics.