leuk                  package:MASS                  R Documentation

_S_u_r_v_i_v_a_l _T_i_m_e_s _a_n_d _W_h_i_t_e _B_l_o_o_d _C_o_u_n_t_s _f_o_r _L_e_u_k_a_e_m_i_a _P_a_t_i_e_n_t_s

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

     A data frame of data from 33 leukaemia patients.

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

     data(leuk)

_F_o_r_m_a_t:

     A data frame with columns:

     `_w_b_c' white blood count

     `_a_g' a test result, `"present"' or `"absent"'

     `_t_i_m_e' survival time in weeks

_S_o_u_r_c_e:

     Cox, D. R. and Oakes, D. (1984) Analysis of Survival Data, 
     Chapman & Hall, p. 9.  Taken from

     Feigl, P. & Zelen, M. (1965) Estimation of exponential survival
     probabilities with concomitant information. Biometrics, 21,
     826-838.

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

     library(survival5)
     data(leuk)
     plot(survfit(Surv(time) ~ ag, data=leuk), lty=2:3, col=2:3)

     # now Cox models
     leuk.cox <- coxph(Surv(time) ~ ag + log(wbc), leuk)
     summary(leuk.cox)

