survfit.object           package:survival           R Documentation

_S_u_r_v_i_v_a_l _C_u_r_v_e _O_b_j_e_c_t

_D_e_s_c_r_i_p_t_i_o_n:

     This class of objects is returned by the 'survfit' class of
     functions to represent a fitted survival curve. 

     Objects of this class have methods for the functions 'print',
     'summary', 'plot', 'points' and 'lines'. The 'print.survfit'
     method does more computation than is typical for a print method
     and is documented on a separate page.

_C_O_M_P_O_N_E_N_T_S:

     The following components must be included in a legitimate
     'survfit' object.

     _t_i_m_e the time points at which the curve has a step.

     _n._r_i_s_k the number of subjects at risk at t.

     _n._e_v_e_n_t the number of events that occur at time t.

     _s_u_r_v the estimate of survival at time t+0. This may be a vector or
          a matrix.

     _s_t_r_a_t_a if there are multiple curves, this component gives the
          number of elements of the 'time' etc. vectors corresponding
          to the first curve, the second curve, and so on.  The names
          of the elements are labels for the curves.

     _s_t_d._e_r_r the standard error of the cumulative hazard or
          -log(survival).

     _u_p_p_e_r upper confidence limit for the survival curve.

     _l_o_w_e_r lower confidence limit for the survival curve.

     _c_o_n_f._t_y_p_e the approximation used to compute the confidence limits.

     _c_o_n_f._i_n_t the level of the confidence limits, e.g. 90 or 95%.

     _n_a._a_c_t_i_o_n the returned value from the na.action function, if any. 
          It will be used in the printout of the curve, e.g., the
          number of observations deleted due to missing values.

     _c_a_l_l the call that produced the object.

_S_U_B_S_C_R_I_P_T_S:

     Survfit objects that contain multiple survival curves can be
     subscripted. This is most often used to plot a subset of the
     curves. Usually a single subscript will be used.  In one
     particular case - survival curves for multiple covariate values,
     from a Cox model that includes a 'strata' statement - there is a
     matrix of curves and 2 subscripts may be used. (In this case
     'summary.survfit' will also print the data as a matrix).

_S_e_e _A_l_s_o:

     'survfit', 'plot.survfit', 'summary.survfit', 'print.survfit'.