gettvc                package:rmutil                R Documentation

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_b_e_f_o_r_e _e_a_c_h _o_b_s_e_r_v_e_d _r_e_s_p_o_n_s_e _a_n_d _p_o_s_s_i_b_l_y _a_d_d _t_h_e_m _t_o _a _l_i_s_t _o_f _o_t_h_e_r
_t_i_m_e-_v_a_r_y_i_n_g _c_o_v_a_r_i_a_t_e_s.

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

     `gettvc' compares the times of response observations with those of
     time-varying covariates to find the most recent observed
     time-varying covariate for each response. These are either placed
     in a new object of class, tvcov, added to an already existing list
     of matrices containing other time-varying covariates and a new
     object of class, tvcov, created, or added to an existing object of
     class, tvcov.

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

     gettvc(response, times=NULL, tvcov=NULL, tvctimes=NULL,
             oldtvcov=NULL, ties=TRUE)

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

response: A list of two column matrices with response values and times
          for each individual, one matrix or dataframe of response
          values, or an object of class, response (created by
          `restovec').

   times: When `response' is a matrix, a vector of possibly unequally
          spaced times for the response, when they are the same for all
          individuals or a matrix of times. Not necessary if equally
          spaced.

   tvcov: A list of two column matrices with time-varying covariate
          values and corresponding times for each individual or one
          matrix or dataframe of such covariate values. Times need not
          be the same as for responses.

tvctimes: When the time-varying covariate is a matrix, a vector of
          possibly unequally spaced times for the covariate, when they
          are the same for all individuals or a matrix of times. Not
          necessary if equally spaced.

oldtvcov: A list of matrices with time-varying covariate values,
          observed at the event times in `response', for each
          individual, or an object of class, tvcov. If not provided, a
          new object is created.

    ties: If TRUE, when the response and covariate times are identical,
          the response depends on that new value (as in observational
          studies); if FALSE, only the next response depends on that
          value (for example, if the covariate is a new treatment just
          applied at that time).

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

     An object of class, tvcov, is returned containing the new
     time-varying covariate and, possibly, those in `oldtvcov'.

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

     J.K. Lindsey and D.F. Heitjan

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

     `carma', `elliptic', `gar', `kalcount', `kalseries', `kalsurv',
     `read.list', `restovec', `tvctomat'.

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

     y <- matrix(rnorm(20), ncol=5)
     resp <- restovec(y, times=c(1,3,6,10,15))
     z <- matrix(rpois(20,5),ncol=5)
     z
     # create a new time-varying covariate object for the response
     newtvc <- gettvc(resp, tvcov=z, tvctimes=c(1,2,5,12,14))
     covariates(newtvc)
     # add another time-varying covariate to the object
     z2 <- matrix(rpois(20,5),ncol=5)
     z2
     newtvc2 <- gettvc(resp, tvcov=z2, tvctimes=c(0,4,5,12,16), oldtvc=newtvc)
     covariates(newtvc2)

