Random Match Probability (RMP) is a kind of measure in population genetics to measure the probability of an unrelated person, randomly picked out of the general population and matching the genotype derived from the evidence.
A genotype has a number of alleles, and each allele has a frequency in a certain race. This frequency is the RMP of that allele. To calculate the RMP of a certain genotype, multiply the frequencies of the alleles in the genotype together. This will give the RMP of the genotype. In forensic science, the evidence from the crime scene is gathered and the genotype of DNA evidence is collected. This is then matched with the suspect. The RMP of the evidence is useful in convincing the jury, because the chances of the genotype of the evidence and that of the suspect matching is very low, and therefore it can hardly be claimed that the suspect is innocent, as the chances of it being so is very low.