The Kaplan-Meier curve is a graphical representation of the survival function, which estimates the probability of survival at each time point in a dataset. It is commonly used in medical research to analyze the survival times of patients and to compare the survival distributions between different groups.
The Kaplan-Meier curve is typically plotted as a step function, where the x-axis represents time and the y-axis represents the estimated probability of survival at each time point. The curve is constructed by calculating the survival probabilities at each distinct time point in the dataset, and then connecting these points with step lines to form the curve.
X-axis (Time): The x-axis represents time, typically in days, months, or years, depending on the unit of measurement used in the dataset. It shows the duration from the start of the study (e.g., date of diagnosis) to the occurrence of events (e.g., death).
The y-axis represents the estimated probability of survival at each time point. It ranges from 0 to 1, where 0 indicates no probability of survival (i.e., all individuals have experienced the event), and 1 indicates full survival (i.e., none of the individuals have experienced the event).
The shape of the survival curve provides insights into the overall survival experience of the population. A steep decline in the curve indicates high mortality rates, while a flat or slowly declining curve suggests better survival outcomes. The curve's slope at any given point reflects the rate of change in survival probability over time.