

strata(survival4)                            R Documentation

_I_d_e_n_t_i_f_y _s_t_r_a_t_a _v_a_r_i_a_b_l_e_s_.

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

     The result is identical to the interaction() function,
     but for the labeling of the factors (strata is more
     verbose).

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

     strata(..., na.group=F)

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

     ...: Any number of variables.  All must be the same
          length.

na.group: if set to T, then missing values are treated as a
          distinct level of each variable.

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

     a new factor, whose levels are all possible combina-
     tions of the factors supplied as arguments.

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

     `coxph'

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

     data(ovarian)
     coxph(Surv(futime, fustat) ~ age + strata(rx))

