Archival Notice
This is an archive page that is no longer being updated. It may contain outdated information and links may no longer function as originally intended.
Home | Glossary | Resources | Help | Contact Us | Course Map
Sometimes a likelihood ratio is converted into a probability. This probability is known as the probability of paternity (POP).20 This formula tests the hypothesis that the alleged father is indeed the biological father of the child. For example, a POP of 99% reflects a 99% probability that the hypothesis is correct and a 1% probability that it is not. The CPI is used in the Bayes formula along with another variable called a prior probability (PP), which represents the social evidence.20 Testing labs typically use a value of 0.5 for the PP on the basis that this is a neutral, unbiased value.16
Mathematically, POP = (100) (CPI) (PP) / [(CPI) (PP) + (1 – PP)]19
POP is not widely used in the United States. A more common approach, similar to the frequentist probability of exclusion, is the Random Man Not Excluded (RMNE) statistic. This is the proportion of the population that could contribute all of the obligate alleles and therefore could not be excluded, or would be falsely included.19 A single locus RMNE is calculated by 1-(1-p)2. Combining the RMNE statistics over all loci gives the combined RMNE (CRMNE), which is equivalent to the CPI. The value of the CRMNE is typically small (less than one), and is analogous to 1-CRMNE or exclusionary power (EP). EP represents the probability of excluding a falsely accused man.19
Although the previous terms and statistics are specific to parentage testing, similar methods are used to estimate the relatedness in other situations, such as identification of human remains and missing persons.
Watch a video on paternity indexes presented by Greggory LaBerge.
Review the YouTube Terms of Service and the Google Privacy Policy
Additional Online Courses
- What Every First Responding Officer Should Know About DNA Evidence
- Collecting DNA Evidence at Property Crime Scenes
- DNA – A Prosecutor’s Practice Notebook
- Crime Scene and DNA Basics
- Laboratory Safety Programs
- DNA Amplification
- Population Genetics and Statistics
- Non-STR DNA Markers: SNPs, Y-STRs, LCN and mtDNA
- Firearms Examiner Training
- Forensic DNA Education for Law Enforcement Decisionmakers
- What Every Investigator and Evidence Technician Should Know About DNA Evidence
- Principles of Forensic DNA for Officers of the Court
- Law 101: Legal Guide for the Forensic Expert
- Laboratory Orientation and Testing of Body Fluids and Tissues
- DNA Extraction and Quantitation
- STR Data Analysis and Interpretation
- Communication Skills, Report Writing, and Courtroom Testimony
- Español for Law Enforcement
- Amplified DNA Product Separation for Forensic Analysts