Cen                   package:NADA                   R Documentation

_C_r_e_a_t_e _a _C_e_n_s_o_r_e_d _O_b_j_e_c_t

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

     Create a censored object, usually used as a response variable in a
     model formula.

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

     Cen(obs, censored, type = "left")

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

     obs: A numeric vector of observations.  This includes both
          censored and uncensored observations. 

censored: A logical vector indicating TRUE where an observation in obs
          is censored (a less-than value) and FALSE otherwise. 

    type: character string specifying the type of censoring. Possible
          values are '"right"', '"left"', '"counting"', '"interval"',
          or '"interval2"'.  The default is '"left"'. 

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

     An object of class 'Cen'.

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

     This, and related routines, are front ends to routines in the
     'survival' package.  Since the survival routines can not handle
     left-censored data, these routines transparently handle
     ``flipping" input data and resultant calculations.  The 'Cen'
     function provides part of the necessary framework for flipping.

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

     Lopaka(Rob) Lee <rclee@usgs.gov>

     Dennis Helsel <dhelsel@usgs.gov>

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

     Helsel, Dennis R. (2005).  Nondectects and Data Analysis;
     Statistics for censored environmental data.  John Wiley and Sons,
     USA, NJ.

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

     'cenfit', 'flip-methods'

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

         obs      = c(0.5,    0.5,   1.0,  1.5,   5.0,    10,   100)
         censored = c(TRUE, FALSE, FALSE, TRUE, FALSE, FALSE, FALSE)

         Cen(obs, censored)
         flip(Cen(obs, censored))

