homerange                package:secr                R Documentation

_H_o_m_e _R_a_n_g_e _S_t_a_t_i_s_t_i_c_s

_D_e_s_c_r_i_p_t_i_o_n:

     Two ad hoc measures of home range size may be calculated in 'secr'
     from capture-recapture data: 

     '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.

_U_s_a_g_e:

     dbar(capthist)
     RPSV(capthist)

_A_r_g_u_m_e_n_t_s:

capthist: object of class 'capthist' 

_D_e_t_a_i_l_s:

     'dbar' is defined as

                            see pdf manual


     'RPSV' is defined as

                            see pdf manual


     'dbar' and 'RPSV' have a specific role as proxies for home-range
     size 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.

_V_a_l_u_e:

     Scalar distance in metres, or a list of such values if 'capthist'
     is a multi-session list.

_N_o_t_e:

     Both measures are affected by the arrangement of detectors. 'dbar'
     is also affected quite strongly by serial correlation in the
     sampled locations. Using 'dbar' with 'proximity' detectors raises
     a problem of interpretation, as the original sequence of multiple
     detections within an occasion is unknown. RPSV is a value
     analogous to the standard deviation of locations about the home
     range centre.

     Inclusion of these measures in the 'secr' package does not mean
     they are recommended for general use! It is usually better to use
     a spatial parameter from a fitted model (e.g., sigma of the
     half-normal detection function). Even then, be careful that sigma
     is not 'contaminated' with behavioural effects (e.g. attraction of
     animal to detector) or 'detection at a distance'.

_A_u_t_h_o_r(_s):

     Murray Efford murray.efford@otago.ac.nz

_R_e_f_e_r_e_n_c_e_s:

     Efford, M. G. (2004) Density estimation in live-trapping studies.
     _Oikos_ *106*, 598-610.

_S_e_e _A_l_s_o:

     'autoini'

_E_x_a_m_p_l_e_s:

     data(captdata)  
     dbar(captdata)
     RPSV(captdata)

