How accurate are the results produced by GCN surveys?

In a comparison of eDNA analysis and conventional methods for GCN survey by professionals across 35 ponds, eDNA analysis achieved a detection rate of 99.3% (139 of 140 samples) compared to bottle trapping (76%), torchlight counts (75%) and egg searches (44%) or torchlight surveys and bottle trapping combined (95%). Across 239 ponds known to support GCN that were sampled for eDNA by volunteers, eDNA analysis achieved a detection rate of 91.3%. For more details, see Biggs et al. (2014).