• We are pleased to announce that the winner of our Feedback Prize Draw for the Winter 2024-25 session and winning £150 of gift vouchers is Zhao Liang Tay. Congratulations to Zhao Liang. If you fancy winning £150 worth of gift vouchers (from a major UK store) for the Summer 2025 exam sitting for just a few minutes of your time throughout the session, please see our website at https://www.acted.co.uk/further-info.html?pat=feedback#feedback-prize for more information on how you can make sure your name is included in the draw at the end of the session.
  • Please be advised that the SP1, SP5 and SP7 X1 deadline is the 14th July and not the 17th June as first stated. Please accept out apologies for any confusion caused.

Kaplan Meier/Nelson Aalen Survival Estimates

L

ldr

Member
Hi
Was just looking for some guidance on the KM and NA survival functions, specifically on the time intervals for the survival estimates

I'm a bit confused on how to write out the for the time interval for the final estimate. Usually for the other ones they follow the following format:
where t(i) is the time of the ith decrement
1..... 0<=t<t(1)
x...... t(1) <=t<t(2)
y...... t(2) <=t<t(3)
etc...
then for the final one ive seen different solutions
sometimes its written as
t(n)<= t <= end of investigation
and sometimes its
t(n)<= t < end of investigation

my confusion is which way the inequality should be as the examiners reports and solutions seem to differ sometimes. For example. CT4 September 2015 Q7 and April 2018 Q10 have different approaches

Thank you
 
The inequality should be t(n)<= t <= end of investigation.

From my Prof's notes, it seems that he adds one last category for both KM and NA estimates, which is t(n)<= t < infinity. This makes the second-last category become t(n)<= t < end of investigation, since you don't double-count within the same interval.
 
You must log in or register to reply here.
Back
Top