Data from: Establishing detection thresholds for environmental DNA using receiver operator characteristic (ROC) curves

Environmental DNA (eDNA) detection is increasingly being used to assess
the potential presence of aquatic species. Setting defensible thresholds
for qPCR assays are necessary to differentiate “detection” from
“non-detection”, but threshold rationales are rarely reported in eDNA
studies. Detection thresholds for data inclusion and exclusion have
implications for downstream data analysis; uncritical acceptance could
result in false positive results (Type I error), whereas overly
conservative thresholds could result in high false negative interpretation
(Type II error). We assessed the use of the receiver operator
characteristics (ROC) framework to identify a detection threshold for
balancing sensitivity and specificity of eDNA data. The ROC framework was
tested using empirical eDNA data from redside dace (Clinostomus
elongatus), an endangered freshwater fish in southwestern Ontario. Based
on negative controls, positive controls, and quality assurance guidelines,
a minimum concentration of 1 copy reaction−1 was identified as the most
appropriate threshold for this study. Although optimal thresholds will
likely vary between studies and labs based on empirical data, the ROC
framework provides a statistical method for establishing defensible
thresholds for data acceptance or rejection as well as tradeoffs between
the sensitivity and specificity of eDNA data.