hurdle                 package:pscl                 R Documentation

_F_i_t _h_u_r_d_l_e _m_o_d_e_l_s _t_o _c_o_u_n_t _d_a_t_a

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

     Estimate a hurdle regression model for count data model via
     maximum likelihood

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

     hurdle(count = y ~ ., x = ~1, z = ~1, data = list(), link = "logit",
             dist = "poisson", method = "BFGS", trace = FALSE,
             maxit = 50000, na.action = na.omit)

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

   count: count being modeled, passed as the left-hand side of a
          'link{formula}'; lowest count must be zero

       x: right-hand side of a formula giving covariates for the count
          part of the model

       z: right-hand side of a formula giving covariates for the hurdle
          part of the model

    data: a data frame

    link: link function for zero-inflated part of the model (choices
          are 'logit' or 'probit')

    dist: count model, '"poisson"' (default) or '"negbin"'

  method: method for maximizing the log-likelihood function, only
          '"BFGS"' and '"Nelder-Mead"' are supported

   trace: logical, if 'TRUE', display progress of maximization

   maxit: maximum number of iterations in maximization

na.action: method for handling missing data, default is 'na.omit'

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

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

     An object of class '"hurdle"'

_N_o_t_e:

     Only minimal support for this class thus far; e.g., no predict
     method

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

     Simon Jackman <jackman@stanford.edu>

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

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

     'zeroinfl', 'summary.hurdle'

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

     data(bioChemists)
     hp <- hurdle(count=art ~ .,
                   x = ~ fem + mar + kid5 + phd + ment,
                   z = ~ fem + mar + kid5 + phd + ment,
                   data=bioChemists,trace=TRUE)
     summary(hp)

     hnb <- hurdle(count=art ~ .,
                   x = ~ fem + mar + kid5 + phd + ment,
                   z = ~ fem + mar + kid5 + phd + ment,
                   dist="negbin",
                   data=bioChemists,trace=TRUE)
     summary(hnb)

