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    Author(s): Matthew C. Fitzpatrick; Evan L. Preisser; Aaron M. Ellison; Joseph S. Elkinton
    Date: 2009
    Source: In: McManus, Katherine A; Gottschalk, Kurt W., eds. Proceedings. 20th U.S. Department of Agriculture interagency research forum on invasive species 2009; 2009 January 13-16; Annapolis, MD. Gen. Tech. Rep. NRS-P-51. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station: 21-23.
    Publication Series: Other
    Station: Northern Research Station
    PDF: View PDF  (134.02 KB)


    Monitoring programs, often comprised of volunteers, increasingly are used to document the spread of forest pests 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 forest pests remains largely unexplored. In this study, we compared the abilities of novice observers and experienced individuals to detect low-density populations of the hemlock woolly adelgid (HWA) and we explore how interobserver variation can bias estimates of the proportion of site infested derived from models.

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    Fitzpatrick, Matthew C.; Preisser, Evan L.; Ellison, Aaron M.; Elkinton, Joseph S. 2009. Observer bias and the detection of low-density infestations: a case study with the hemlock woolly adelgid

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