From page 26, chapter 2 of the reference "Tableman, M., & Kim, J. S. (2003). Survival analysis using S: analysis of time-to-event data. CRC press", I have found the definition of the empirical survivor function (esf) is
S(t) = (number of individuals > t)/n .
But from page 80, chapter 3 of the reference "Lawless, J. F. (2011). Statistical models and methods for lifetime data (Vol. 362). John Wiley & Sons",
esf, S(t) = (number of individuals >= t)/n .
Which formula is correct?
Consider a lifetime data:
t = 9 13 13 18 33 28 31 34
By the definition of esf from the first reference, S(18)= 4/8=0.5.
By the definition of esf from the second reference, S(18)= 5/8=0.625.
Which one is conventional?
Thanks for your attention.
S(t) = (number of individuals > t)/n .
But from page 80, chapter 3 of the reference "Lawless, J. F. (2011). Statistical models and methods for lifetime data (Vol. 362). John Wiley & Sons",
esf, S(t) = (number of individuals >= t)/n .
Which formula is correct?
Consider a lifetime data:
t = 9 13 13 18 33 28 31 34
By the definition of esf from the first reference, S(18)= 4/8=0.5.
By the definition of esf from the second reference, S(18)= 5/8=0.625.
Which one is conventional?
Thanks for your attention.