

cluster(survival4)                           R Documentation

_I_d_e_n_t_i_f_y _c_l_u_s_t_e_r_s

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

     This is a special function used in the context of the
     Cox model.  It identifies correlated groups of observa-
     tions, and is used on the right hand side of a formula.

_U_s_a_g_e_:

     cluster(x)

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

       x: A character, factor, or numeric variable.

_V_a_l_u_e_:

     The function's only action is semantic, to mark a vari-
     able as the cluster indicator.

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

     `coxph'

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

     data(ovarian)
     coxph(Surv(futime, fustat) ~ age + cluster(group))

