TY - JOUR
T1 - Estimating the encounter rate variance in distance sampling
AU - Fewster, RM
AU - Buckland, Stephen Terrence
AU - Burnham, KP
AU - Borchers, David Louis
AU - Jupp, P E
AU - Laake, JL
AU - Thomas, Len
PY - 2009/3
Y1 - 2009/3
N2 - The dominant source of variance in line transect sampling is usually the encounter rate variance. Systematic survey designs are often used to reduce the true ariability among different realizations of the design, but estimating the variance is difficult and estimators typically approximate the variance by treating the design as a simple random sample of lines. We explore the properties of different encounter rate variance estimators under random and systematic designs. We show that a design-based variance estimator improves upon the model-based estimator of Buckland et al. (2001, Introduction to Distance Sampling. Oxford: Oxford University Press, p. 79) when transects are positioned at random. However, if populations exhibit strong spatial trends, both estimators can have substantial positive bias under systematic designs. We show that poststratification is effective in reducing this bias.
AB - The dominant source of variance in line transect sampling is usually the encounter rate variance. Systematic survey designs are often used to reduce the true ariability among different realizations of the design, but estimating the variance is difficult and estimators typically approximate the variance by treating the design as a simple random sample of lines. We explore the properties of different encounter rate variance estimators under random and systematic designs. We show that a design-based variance estimator improves upon the model-based estimator of Buckland et al. (2001, Introduction to Distance Sampling. Oxford: Oxford University Press, p. 79) when transects are positioned at random. However, if populations exhibit strong spatial trends, both estimators can have substantial positive bias under systematic designs. We show that poststratification is effective in reducing this bias.
KW - Distance sampling
KW - Encounter rate
KW - Line transect sampling
KW - Point transect sampling
KW - Stratified variance estimators
KW - Systematic sampling
KW - Variance estimation
UR - http://www.scopus.com/inward/record.url?scp=62749206219&partnerID=8YFLogxK
U2 - 10.1111/j.1541-0420.2008.01018.x
DO - 10.1111/j.1541-0420.2008.01018.x
M3 - Article
SN - 0006-341X
VL - 65
SP - 225
EP - 236
JO - Biometrics
JF - Biometrics
IS - 1
ER -