title: Count data, detection probabilities, and the demography, dynamics, distribution, and decline of amphibians.
abstract: The evidence for amphibian population declines is based on count data that were not adjusted for detection probabilities. Such data are not reliable even when collected using standard methods. The formula C = Np (where C is a count, N the true parameter value, and p is a detection probability) relates count data to demography, population size, or distributions. With unadjusted count data, one assumes a linear relationship between C and N and that p is constant. These assumptions are unlikely to be met in studies of amphibian populations. Amphibian population data should be based on methods that account for detection probabilities.
authors.affiliation: Zoologisches Institut, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland. bschmidt@zool.unizh.ch
authors.forename: Benedikt R
authors.initials: BR
authors.lastname: Schmidt
mesh_terms: D000663:Amphibians; D000818:Animals; D003247:Conservation of Natural Resources / Q000379:methods*; D003710:Demography; D011157:Population Dynamics; D011336:Probability; D015203:Reproducibility of Results; D013557:Switzerland