baro5                  package:drc                  R Documentation

_T_h_e _m_o_d_i_f_i_e_d _b_a_r_o_5 _f_u_n_c_t_i_o_n

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

     'baro5' allows specification of the baroreflex 5-parameter dose
     response function, under various constraints on the parameters.

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

       baro5(fixed = c(NA, NA, NA, NA, NA), names = c("b1", "b2", "c", "d", "e"),
       method = c("1", "2", "3", "4"), ssfct = NULL)

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

   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 order of the
          parameters is: b1, b2, c, d, e (see under 'Details').

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

   ssfct: a self starter function to be used.

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

     The five-parameter function given by the expression


 y = c + frac{d-c}{1+fexp(b1(log(x)-log(e))) + (1-f)exp(b2(log(x)-log(e)))}



           f = 1/( 1 + exp((2b1b2/|b1+b2|)(log(x)-log(e))))


     If the difference between the parameters b1 and b2 is different
     from 0 then the function is asymmetric.

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

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

_N_o_t_e:

     See the example for the dataset 'heartrate'.

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

     Christian Ritz

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

     Ricketts, J. H. and Head, G. A. (1999)  A five-parameter logistic
     equation for investigating asymmetry of curvature in baroreflex
     studies.  _Am. J. Physiol. (Regulatory Integrative Comp. Physiol.
     46)_, *277*, 441-454.

