drfit                 package:drfit                 R Documentation

_F_i_t _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:

     Fit dose-response relationships to dose-response data and
     calculate biometric results for (eco)toxicity evaluation

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

       drfit(data, startlogEC50 = NA, lognorm = TRUE, logis = FALSE, 
         linearlogis = FALSE, b0 = 2, f0 = 0)

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

    data: A data frame as returned from 'drdata'.  The data frame has
          to contain at least a factor called "substance", a vector
          called "unit" containing the unit used for the dose, a column
          "response" with the response values of the test system
          normalized between 0 and 1 and a column "dose" with the
          numeric dose values. For later use of the 'drplot' function,
          a factor called "dosefactor" also has to be present,
          containing the dose as a factor. 

startlogEC50: Especially for the linearlogis model, a suitable log10 of
          the EC50 has to be given  by the user, since it is not
          correctly estimated for data showing hormesis with the
          default estimation method.

 lognorm: A boolean defining if cumulative density curves of normal
          distributions are fitted to the data. Default ist TRUE.

   logis: A boolean defining if cumulative densitiy curves of logistic
          distributions are fitted to the data. Default is FALSE.

linearlogis: A boolean defining if the linear-logistic function as
          defined by van Ewijk and Hoekstra 1993 is fitted to the data.
          Default is FALSE.

   b0,f0: If the linearlogistic model is fitted, b0 and f0 give the
          possibility to adapt the starting values for the parameters b
          and f.

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

 results: A data frame containing at least one line for each substance.
          If the data did not show a mean response < 0.5 at the highest
          dose level, the modeltype is set to "none". Every successful
          fit is reported in one line. Parameters of the fitted curves
          are only reported if the fitted EC50 is not higher than the
          highest dose.

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

     Johannes Ranke  jranke@uni-bremen.de  <URL:
     http://www.uft.uni-bremen.de/chemie/ranke>

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

     data(antifoul)
     r <- drfit(antifoul)
     format(r,digits=2)

