A match statistic
A fictional classroom exercise states that a complete DNA profile has a random-match probability of one in one million under an explicitly defined unrelated-person population model. It does not provide prior odds, the number of plausible contributors, a complete mixture assessment, an error-rate calculation or the circumstances in which the biological material was deposited. An investigator says that the statistic means there is only a one-in-one-million probability that the named person is innocent. The analyst must distinguish the reported profile statistic from a posterior conclusion about guilt. The case concerns transparent interpretation of supplied probabilities rather than assessment of an actual suspect or a court standard.
1. Interpret the central finding or reasoning problem.
Read the worked answer
The statistic concerns the probability of a matching profile under the specified unrelated-person model; it is not the probability of innocence.
2. State the principal limitation and next reasoning requirement.
Read the worked answer
The alternative proposition, prior information, laboratory limitations and relevance of deposition remain separate issues that cannot be supplied by reversing the conditional probability.