kaplanmeierkaavio

Kaplan Meier kaavio, also known as a Kaplan Meier curve, is a non-parametric statistic used to estimate the survival function from lifetime data. It is particularly useful in medical research and other fields where it is important to understand the time until a specific event occurs, such as death, disease recurrence, or equipment failure. The curve plots the probability of survival over time, showing how the likelihood of the event changes as more time passes.

The Kaplan Meier method works by calculating the proportion of individuals who are still "alive" (i.e., have not experienced the event of interest) at each time point where an event occurs. When an event occurs, the survival probability is multiplied by the proportion of individuals who survived up to that point. Censored observations, where an individual is lost to follow-up or the study ends before the event occurs, are handled by excluding them from the denominator of the calculation at the time they are censored, but including them in the denominator for all preceding time points.

The resulting Kaplan Meier curve is a step function, where the steps represent the times at which events occur. The curve typically starts at 1 (representing 100% survival) and decreases over time. The shape of the curve provides insights into the survival experience of the group being studied. For example, a rapid decline in the curve indicates a high risk of the event occurring early in the observation period. The method is widely used for comparing survival rates between different groups, such as comparing a treatment group to a control group.