Combined Paternity Index (CPI) | DNA Testing Glossary
The combined paternity index (CPI) is a single number that represents the overall statistical weight of the DNA evidence across all tested loci in a paternity case. At each locus, the lab calculates a paternity index — a ratio comparing the likelihood that the alleged father contributed the child's allele versus the likelihood that a random unrelated man from the same population could have contributed it. The CPI is the product of all individual paternity indices multiplied together. A CPI of 10,000, for example, means the alleged father is 10,000 times more likely to be the biological father than a random man. The CPI is then converted to a probability of paternity (typically 99.99% or higher for an inclusion).
Related Terms
Probability of Paternity, Allele, Locus, Inclusion, Exclusion
