dbar is the mean distance between consecutive capture locations,
pooled over individuals (e.g. Efford 2004).
RPSV (for 'Root Pooled Spatial Variance') is a measure of the 2-D
dispersion of the locations at which individual animals are detected,
pooled over individuals.dbar(capthist)
RPSV(capthist)capthistcapthist
is a multi-session list.dbar is defined as
$$\overline{d}=\frac{\sum\limits _{i=1}^{n}
\sum\limits _{j=1}^{n_i - 1}
\sqrt{(x_{i,j}-x_{i,j+1})^2 + (y_{i,j}-y_{i,j+1})^2}}
{\sum\limits _{i=1}^{n} (n_i-1)}$$
RPSV is defined as
$$RPSV = \sqrt{
\frac {\sum\limits _{i=1}^{n} \sum\limits _{j=1}^{n_i} [
(x_{i,j} - \overline x_i)^2 + (y_{i,j} - \overline y_i)^2
]}{\sum\limits _{i=1}^{n} (n_i-1) - 1}}$$
dbar and RPSV have a specific role as proxies for
detection scale in inverse-prediction estimation of density (Efford
2004; see ip.secr).
dbar is used in autoini to obtain plausible starting
values for maximum likelihood estimation.autoinidata(captdata)
dbar(captdata)
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