fplogistic                package:drc                R Documentation

_F_r_a_c_t_i_o_n_a_l _p_o_l_y_n_o_m_i_a_l-_l_o_g_i_s_t_i_c _d_o_s_e-_r_e_s_p_o_n_s_e _m_o_d_e_l_s

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

     Model function for specifying dose-response models that are a
     combination of a logistic model and an appropriate  class of
     fractional polynomials.

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

     fplogistic(p1, p2, fixed = c(NA, NA, NA, NA), names = c("b", "c", "d", "e"), 
     method = c("1", "2", "3", "4"), ssfct = NULL, fctName, fctText)

     FPL.4(p1, p2, fixed = c(NA, NA, NA, NA), names = c("b", "c", "d", "e"), ...)

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

      p1: numeric denoting the negative power of log(dose+1) in the
          fractional polynomial.

      p2: numeric denoting the positive power of log(dose+1) in the
          fractional polynomial.

   fixed: numeric vector. Specifies which parameters are fixed and at
          what value they are fixed.  NAs for parameter that are not
          fixed.

   names: a vector of character strings giving the names of the
          parameters (should not contain ":"). The default is
          reasonable (see under 'Usage'). The order of the parameters
          is: b, c, d, e, f  (see under 'Details').

  method: character string indicating the self starter function to use.

   ssfct: a self starter function to be used.

 fctName: optional character string used internally by convenience
          functions.

 fctText: optional character string used internally by convenience
          functions.

     ...: Additional arguments (see 'fplogistic').

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

     The fractional polynomial dose-response models introduced by
     Namata _et al._ (2008) are implemented using the logistic model as
     base.

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

     The value returned is a list containing the nonlinear function,
     the self starter function and the parameter names.

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

     Christian Ritz

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

     Namata, Harriet and Aerts, Marc and Faes, Christel and Teunis,
     Peter (2008) Model Averaging in Microbial Risk Assessment Using
     Fractional Polynomials, _Risk Analysis_ *28*, 891-905.

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

     Examples are found 'maED'.

