selviytymiskäyrästä

Selviytymiskäyrä, often translated as survival curve, is a fundamental concept in survival analysis used to depict the probability of an event occurring over time. This event could be anything from the failure of a machine component to the death of a patient or the discontinuation of a customer relationship. The curve graphically represents the proportion of individuals or items that have survived (i.e., have not experienced the event) at various points in time.

The horizontal axis of a survival curve typically represents time, while the vertical axis shows the proportion of survivors. Initially, at time zero, the proportion of survivors is usually 1 (or 100%), indicating that all subjects are still event-free. As time progresses, the curve generally declines, reflecting the cumulative occurrence of the event. A steep decline signifies a rapid increase in the event rate, whereas a flatter slope indicates a slower progression.

Key features of a survival curve include its starting point, its overall shape, and its end point. The curve can be influenced by various factors and is often used to compare survival experiences between different groups, such as patients receiving different treatments or products from different manufacturers. The median survival time, the time at which 50% of the subjects have experienced the event, is a commonly derived statistic from a survival curve. It provides a concise measure of the typical survival experience.