glm.convert               package:MASS               R Documentation

_C_h_a_n_g_e _a _N_e_g_a_t_i_v_e _B_i_n_o_m_i_a_l _f_i_t _t_o _a _G_L_M _f_i_t

_D_e_s_c_r_i_p_t_i_o_n:

     This function modifies an output object from 'glm.nb()' to one
     that looks like the output from 'glm()' with a negative binomial
     family.  This allows it to be updated keeping the theta parameter
     fixed.

_U_s_a_g_e:

     glm.convert(object)

_A_r_g_u_m_e_n_t_s:

  object: An object of class '"negbin"', typically the output from
          'glm.nb()'. 

_D_e_t_a_i_l_s:

     Convenience function needed to effect some low level changes to
     the structure of the fitted model object.

_V_a_l_u_e:

     An object of class '"glm"' with negative binomial family.  The
     theta parameter is then fixed at its present estimate.

_S_e_e _A_l_s_o:

     'glm.nb', 'negative.binomial', 'glm'

_E_x_a_m_p_l_e_s:

     quine.nb1 <- glm.nb(Days ~ Sex/(Age + Eth*Lrn), data = quine)
     quine.nbA <- glm.convert(quine.nb1)
     quine.nbB <- update(quine.nb1, . ~ . + Sex:Age:Lrn)
     anova(quine.nbA, quine.nbB)

