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===Survivor function===
===Survivor function===
The survival function (also known as the '''cumulative survival probability''') describes the proportion of initially disease-free individuals who have not experienced the outcome of interest over time, and so is similar conceptually to the incidence risk. The survival time may be visualised using a Kaplan-Meier curve, or may be summarised using the ''survival time''. Survival time is measured in units of time and describes the time until animals experience disease. Commonly, the '''median survival time''' is presented, which is the time at which 50% of the population have experienced the event (this is the most appropriate measure of the 'average' survival time, as the mean would not be able to account for individuals who have not experienced the outcome by the end of the study). However, if 50% of the individuals have not experienced disease by the end of the study, the median survival time cannot be calculated. Another option is to describe the proportion of individuals who have not experienced disease at a set point in time, which is the same concept as the [[incidence risk|Incidence risk]]
The survival function (also known as the '''cumulative survival probability''') describes the proportion of initially disease-free individuals who have not experienced the outcome of interest over time, and so is similar conceptually to the incidence risk. The survival time may be visualised using a Kaplan-Meier curve, or may be summarised using the ''survival time''. Survival time is measured in units of time and describes the time until animals experience disease. Commonly, the '''median survival time''' is presented, which is the time at which 50% of the population have experienced the event (this is the most appropriate measure of the 'average' survival time, as the mean would not be able to account for individuals who have not experienced the outcome by the end of the study). However, if 50% of the individuals have not experienced disease by the end of the study, the median survival time cannot be calculated. Another option is to describe the proportion of individuals who have not experienced disease at a set point in time, which is the same concept as the [[#Incidence risk|incidence risk]]
===Hazard function===
===Hazard function===