Cook's Distances             package:car             R Documentation

_C_o_o_k'_s _D_i_s_t_a_n_c_e_s _f_o_r _L_i_n_e_a_r _a_n_d _G_e_n_e_r_a_l_i_z_e_d _L_i_n_e_a_r _M_o_d_e_l_s

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

     This function now simply calls 'cooks.distance' in the 'base'
     package.

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

     cookd(model, ...)

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

   model: 'lm' or 'glm' model object.

     ...: other arguments to be passed to 'cooks.distance'.

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

     Cook's distances for generalized linear models are approximations,
     as described in Williams (1987) (except that the Cook's distances
     are scaled as _F_ rather than as chi-square values).

     This function is retained primarily for consistency with _An R and
     S-PLUS Companion to Applied Regression._ Other deletion
     diagnostics formerly in the 'car' package have been rewritten and
     moved to the 'base' package; these include 'influence', 
     'rstudent', 'hatvalues', 'dfbeta', and 'dfbetas'.

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

     'cookd' returns a vector with one entry for each observation.

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

     John Fox jfox@mcmaster.ca

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

     Cook, R. D. and Weisberg, S. (1984) _Residuals and Influence in
     Regression._ Wiley.

     Fox, J. (1997) _Applied Regression, Linear Models, and Related
     Methods._ Sage.

     Williams, D. A. (1987) Generalized linear model diagnostics using
     the deviance and single case deletions. _Applied Statistics_ *36*,
     181-191.

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

     'cooks.distance', 'influence'

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

     data(Duncan)
     attach(Duncan)
     mod <- lm(prestige ~ income + education)
     plot(cookd(mod))

