mixture                 package:drc                 R Documentation

_F_i_t_t_i_n_g _m_i_x_t_u_r_e _m_o_d_e_l_s

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

     'mixture' fits a concentration addition, Hewlett or Voelund model
     to data from mixture toxicity experiments.

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

       mixture(object, model = c("CA", "Hewlett", "Voelund"), start, startm, control = drmc())

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

  object: object of class 'drc' corresponding to the model with freely
          varying EC50 values.

   model: character string. It can be "CA", "Hewlett" or "Voelund".

   start: optional numeric vector supplying starting values for all
          parameters in the mixture model.

  startm: optional numeric vector supplying the lambda parameter in the
          Hewlett model or  the eta parameters (two parameters) in the
          Voelund model.

 control: list of arguments controlling constrained optimisation (zero
          as boundary),  maximum number of iteration in the
          optimisation, relative tolerance in the optimisation,
          warnings issued during the optimisation.

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

     The function is a wrapper to 'drm', implementing the models
     described in Soerensen et al. (2007).  See the paper for a
     discussion of the merits of the different models.

     Currently only the log-logistic models are available. Application
     of Box-Cox transformation is not yet available.

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

     An object of class 'drc' with a few additional components.

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

     Christian Ritz

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

     Soerensen, H. and Cedergreen, N. and Skovgaard, I. M. and
     Streibig, J. C. (2007)  An isobole-based statistical model and
     test for synergism/antagonism in binary mixture toxicity
     experiments,  _Environmental and Ecological Statistics_, *14*,
     383-397.

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

     The examples in 'acidiq' (the Hewlett model), 'glymet'
     (concentration addition)  and 'mecter' (the Voelund model).

