We hope that when new assays are published, reference will be made to this scale as a standardised way to communicate the extent to which they have been validated. It will help end users to decide whether or not an assay is suitable for their needs in terms of its level of validation and reporting, and regarding the remaining uncertainties around positive or negative results. The validation scale can also guide next steps for the advancement of assays in order to move them further along the scale.

Please note that the validation scale functions as a general framework, and that future technological advances and knowledge gains can make changes in the structure necessary. The scale was originally developed at a DNAqua-net (Working Group 3: field and laboratory methods) workshop in Innsbruck, Austria, in March 2018. For a complete assessment of targeted eDNA validation and reporting practices, please see Thalinger et al. (https://doi.org/10.1101/2020.04.27.063990)