Observer Bias and the Detection of Low-Density Populations

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Observer Bias and the Detection of Low-Density Populations

Show simple item record Elkinton, Joseph Ellison, Aaron Preisser, Evan Fitzpatrick, Matthew 2009-06-29T18:14:10Z 2009
dc.identifier.citation Fitzpatrick, Matthew C., Evan L. Preisser, Aaron M. Ellison, and Joseph S. Elkinton. Forthcoming. Observer bias and the detection of low-density populations. Ecological Applications 19. en
dc.identifier.issn 1051-0761 en
dc.description.abstract Monitoring programs increasingly are used to document the spread of invasive species in the hope of detecting and eradicating low-density infestations before they become established. However, interobserver variation in the detection and correct identification of low-density populations of invasive species remains largely unexplored. In this study, we compare the abilities of volunteer and experienced individuals to detect low-density populations of an actively spreading invasive species and we explore how interobserver variation can bias estimates of the proportion of sites infested derived from occupancy models that allow for both false negative and false positive (misclassification) errors. We found that experienced individuals detected small infestations at sites where volunteers failed to find infestations. However, occupancy models erroneously suggested that experienced observers had a higher probability of falsely detecting the species as present than did volunteers. This unexpected finding is an artifact of the modeling framework and results from a failure of volunteers to detect low-density infestations rather than from false positive errors by experienced observers. Our findings reveal a potential issue with site occupancy models that can arise when volunteer and experienced observers are used together in surveys. en
dc.description.sponsorship Other Research Unit en
dc.language.iso en_US en
dc.publisher Ecological Society of America en
dc.relation.isversionof en
dash.license LAA
dc.subject volunteer en
dc.subject survey en
dc.subject site occupancy models en
dc.subject occurence probability en
dc.subject monitoring en
dc.subject invasive species en
dc.subject hemlock wooly adelgid en
dc.subject citizen science en
dc.title Observer Bias and the Detection of Low-Density Populations en
dc.relation.journal Ecological Applications en Ellison, Aaron

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