# Estimation of a Survival Function

In the context of physical asset management, I have read that the Kaplan-Meier estimate is a useful tool for estimating the survival function, based on failure dates for a set of items which were all installed at the same time.

If I have the failure dates for a set of items which were $\textbf{not}$ necessarily installed at the same time and I have their installation dates, what methods can I use to estimate the survival function?

• @StatsPlease There is no left-truncation. Before installation, items are not at risk at all..... After installation, items are under observation immediately and there is no delay between risk onset and start of the observation. – jujae Feb 15 '17 at 16:51