Kaplan–Meier estimator & Greenwood formula

The Kaplan–Meier estimator (also known as the product limit estimator) estimates the survival function from life-time data. In medical research, it might be used to measure the fraction of patients living for a certain amount of time after treatment. An economist might measure the length of time people remain unemployed after a job loss. An engineer might measure the time until failure of machine parts. An ecologist may use it to estimate how long fleshy fruits remain on plants before they are removed by frugivores.