Research Article| Volume 16, P226-231, May 2015

p-Values should not be used for evaluating the strength of DNA evidence

Published:January 30, 2015DOI:


      • p-Values have recently been proposed for interpreting DNA evidence instead of likelihood ratios.
      • p-Values do not relate to the strength of DNA evidence.
      • Evaluating DNA evidence using p-values can be problematic and misleading.
      • Examples from mixture interpretation and kinship testing demonstrate the problems associated with p-values.


      Recently, p-values have been suggested to explain the strength of a likelihood ratio that evaluates DNA evidence. It has been argued that likelihood ratios would be difficult to explain in court and that p-values would offer an alternative that is easily explained. In this article, we argue that p-values should not be used in this context. p-Values do not directly relate to the strength of the evidence. The likelihood ratio measures the strength of the evidence, while the p-value measures how rare it is to find evidence that is equally strong or stronger, which is something fundamentally different. In addition, a p-value is not always unambiguous. To illustrate our arguments, we present several examples from forensic genetics.


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