What do you mean by false positive?. Issue 5 (2nd May 2021) - Darling, John A.
Abstract: Misunderstandings regarding the term "false positive" present a significant hurdle to broad adoption of eDNA monitoring methods. Here, we identify three challenges to clear communication of false‐positive error between scientists, managers, and the public. The first arises from a failure to distinguish between false‐positive eDNA detection at the sample level and false‐positive inference of taxa presence at the site level. The second is based on the large proportion of false positives that may occur when true‐positive detections are likely to be rare, even when rates of contamination or other error are low. And the third misunderstanding occurs when conventional species detection approaches, often based on direct capture, are used to confirm eDNA approaches without acknowledging or quantifying the conventional approach's detection probability. The solutions to these issues include careful and consistent communication of error definitions, managing expectations of error rates, and providing a balanced discussion not only of alternative sources of species DNA, but also of the detection limitations of conventional methods. We argue that the benefit of addressing these misunderstandings will be increased confidence in the utility of eDNA methods and, ultimately, improved resource management using eDNA approaches. Abstract : The term false positive is often misused in eDNA research and natural resource management. There are issues of scale of inference, the base rate fallacy, and confirmation errors using conventional methods of detection. We offer a perspective to guide discussions of errors in species detection.