

motors(MASS)                                 R Documentation

_A_c_c_e_l_e_r_a_t_e_d _L_i_f_e _T_e_s_t_i_n_g _o_f _M_o_t_o_r_e_t_t_e_s

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

     The `motorette' data frame has 40 rows and 3 columns.
     It describes an accelerated life test at each of four
     temperatures of 10 motorettes, and has rather discrete
     times.

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

    temp: the temperature (degrees C) of the test

    time: the time in hours to failure or censoring at 8064
          hours (= 336 days).

    cens: an indicator variable for death

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

     This data frame contains the following columns:

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

     Kalbfleisch, J. D. and Prentice, R. L. (1980) The Sta-
     tistical Analysis of Failure Time Data.  New York:
     Wiley.

     taken from

     Nelson, W. D. and Hahn, G. J. (1972) Linear regression
     of a regression relationship from censored data.  Part
     1 - simple methods and their application.  Technomet-
     rics 14, 247-276.

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

     library(survival5)
     data(motors)
     plot(survfit(Surv(time, cens) ~ factor(temp), motors), conf.int=FALSE)
     # fit Weibull model
     motor.wei <- survreg(Surv(time, cens) ~ temp, motors)
     summary(motor.wei)
     # and predict at 130C
     unlist(predict(motor.wei, data.frame(temp=130), se.fit=TRUE))

     motor.cox <- coxph(Surv(time, cens) ~ temp, motors)
     summary(motor.cox)
     # predict at temperature 200
     plot( survfit(motor.cox, newdata=data.frame(temp=200),
          conf.type="log-log") )
     summary( survfit(motor.cox, newdata=data.frame(temp=130)) )

