descriptive             package:Rcapture             R Documentation

_D_e_s_c_r_i_p_t_i_v_e _S_t_a_t_i_s_t_i_c_s

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

     This function produces descriptive statistics for
     capture-recapture data.

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

     descriptive(X, dfreq=FALSE)

     ## S3 method for class 'descriptive':
     print(x, ...)

     ## S3 method for class 'descriptive':
     plot(x, ...)

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

       X: The table of the observed capture histories in one of the two
          accepted formats. In the default format, it has one row per
          unit captured in the experiment. In this case, the number of
          columns in the table represents the number of capture
          occasions in the experiment (noted t). In the alternative
          format, it contains one row per capture history followed by
          its frequency. In that case, 'X' has t+1 columns. The first t
          columns of 'X', identifying the capture histories, must
          contain only zeros and ones. The number one indicates a
          capture. 

   dfreq: This argument specifies the format of the data matrix 'X'. By
          default, it is set to FALSE, which means that 'X' has one row
          per unit. If it is set to TRUE, then the matrix 'X' contains
          frequencies in its last column.

       x: An object, produced by the 'descriptive' function, to print
          or to plot.

     ...: Further arguments passed to or from other methods.

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

     The 'plot.descriptive' function produces exploratory heterogeneity
     graphs. In absence of heterogeneity, the relations presented in
     the two graphs should be almost linear. Convex fonctions indicate
     heterogeneity.

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

       n: The total number of captured units.

base.freq : A table of basic descriptive statistics. For i=1,...,t :

     _f_i the number of units captured i times

     _u_i the number of units captured for the first time on occasion i 

     _v_i the number of units captured for the last time on occasion i 

     _n_i the number of units captured on occasion i . 

m.array : A t by t matrix containing recapture statistics for units
          released on occasion i, for i=1,...,t :

     _n_i the number of units captured on occasion i 

     _c_2 the number of units caught on occasion i recaptured for the
          first time on occasion 2 
           ....

     _c_t the number of units caught on occasion i recaptured for the
          first time on occasion t 

     _n_o_t _r_e_c_a_p_t the number of units caught on occasion i never
          recaptured. 

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

     Sophie Baillargeon sbaillar@mat.ulaval.ca and Louis-Paul Rivest
     lpr@mat.ulaval.ca

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

     Baillargeon, S. and Rivest, L.P. (2007). The Rcapture package:
     Loglinear models for capture-recapture in R. _Journal of
     Statistical Software_, to appear (available online at <URL:
     http://www.jstatsoft.org/>).

     Lindsay, B. G. (1986) Exponential family mixture models (with
     least-squares estimators).  _ Annals of Statistics_, 14, 124-137.

     Rivest, L.P. (2007). Why a time effect has a limited impact on
     capture-recapture estimates in closed populations. _The Canadian
     Journal of Statistics_, under revision.

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

     data(hare)
     desc<-descriptive(hare)
     desc
     plot(desc)

