How many or more likelihood ratios are required?

Summary of this article

Likelihood ratios are important in DNA testing. How many or more is considered a reliable result? Learn more about the criteria that will help you interpret appraisal results.

In paternity and DNA testing, the likelihoodmetaphor(Likelihood Ratio, LR)</a9> is an indicator used to determine whether or not the test results support a parent-child relationship. The higher the likelihood ratio, the more likely it is that a parent-child relationship is established.

General criteria.

Likelihood ratio greater than 1,000: strong support for a parent-child relationship (high confidence).
Likelihood ratio greater than 10,000: there is very strong support for a parent-child relationship (very high confidence).

According to many legal standards and international guidelines, a parent-child relationship is considered ‘almost certainly established’ if the likelihood ratio is above 10,000.At this level, the likelihood of other unrelated individuals being matched by chance is extremely low.

Interpretation notes.

Dependent on the situation and the standard used: the interpretation of the likelihood ratio may depend on legal requirements and the standard used. For example, in some legal proceedings, a lower likelihood ratio may be accepted as establishing a parent-child relationship.
Context-dependent: the context of the examination and additional evidence are important for the interpretation of the likelihood ratio. For example, a slightly lower likelihood ratio may be considered sufficient if other evidence or circumstances strongly support a parent-child relationship.

Summary

Generally, a parent-child relationship is considered to be significantly established if the likelihood ratio is 10,000 or more. However, specific criteria vary according to legal requirements and the case, so it is recommended that expert advice is sought.