KaplanMeierkäyrien

Kaplan Meierkäyrien, also known as survival curves, are a non-parametric statistical method used to estimate the survival function from lifetime data. The survival function, denoted S(t), represents the probability that an individual will survive beyond a specific time t. These curves are particularly useful in fields such as medicine, engineering, and social sciences where the time until an event of interest (e.g., death, failure, recurrence) is being studied.

The Kaplan-Meier estimator works by calculating the proportion of individuals who have survived at each observed event time. The curve begins at a survival probability of 1 (100%) at time zero and decreases stepwise whenever an event occurs. Censoring is a key aspect handled by this method. Censored individuals are those for whom the event of interest has not occurred by the end of the study or for whom the event status is otherwise unknown. The Kaplan-Meier estimator accounts for censoring by adjusting the survival probability calculation at each event time, effectively removing censored individuals from the risk set at the time of their censoring.

Visually, a Kaplan-Meier curve is a graph with time on the x-axis and the estimated survival probability on the y-axis. The steps in the curve indicate the times at which events occurred. The steeper the drop in the curve, the higher the rate of events at that time. Comparing multiple Kaplan-Meier curves, for instance, for different treatment groups, allows for visual assessment of differences in survival experiences. Statistical tests, such as the log-rank test, are often used in conjunction with Kaplan-Meier curves to formally test for significant differences between survival distributions.