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Productivity Estimates From Upland Bird Harvests: Estimating Variance and Necessary Sample Sizes
Author(s) -
HAGEN CHRISTIAN A.,
LOUGHIN THOMAS M.
Publication year - 2008
Publication title -
the journal of wildlife management
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.94
H-Index - 111
eISSN - 1937-2817
pISSN - 0022-541X
DOI - 10.2193/2007-390
Subject(s) - productivity , statistics , sample (material) , confidence interval , variance (accounting) , sample size determination , population , sampling (signal processing) , mathematics , econometrics , demography , computer science , economics , chemistry , accounting , filter (signal processing) , chromatography , sociology , computer vision , macroeconomics
Harvest of upland game birds in concert with sampling of age ratios from wings can yield important biological information about populations. Although estimates of productivity are commonly produced, they are often not accompanied by a measure of variance. Thus, we developed standard error estimates for sample productivity ratios, compared 4 methods for creating confidence intervals for population productivity ratios, and developed a test and the corresponding sample size requirements for comparing 2 population productivity ratios. We applied these techniques to greater sage‐grouse ( Centrocercus urophasianus ) wing‐data collected in Oregon, USA (1993–2005). Computer simulations indicated that backtransforming the Wilson's score interval on the proportion of immatures in the sample results in the most reliable confidence intervals among the methods considered. We recommend to managers measuring conservation action outcomes with productivity ratios to consider the appropriate sample sizes for the spatial and temporal scale of their monitoring programs.