Question

State and explain two types of censoring giving examples

Answer 1

Right censoring.Right-censoring occurs when the true unobserved event is to the right of the censored time; i.e., all that is known is that the event has not happened at the end of follow-up. This most common type of censoring dealt with in survival analysis.There are generally three reasons why right censoring may occur:
• termination the study ;
• loss of follow-up during the study period;
• withdrawal from the study

Left-censoring: This can occur when a persons true survival time is less than
or equal to that persons observed survival time. For example, if we are following persons until they become HIV positive, we may record a failure when a subject first tests positive for the virus. However, we may not know the exact time of first exposure to the virus, and therefore do not know exactly when the failure occurred.Thus, the survival time is censored on the left side since the true survival time, which ends at exposure, is shorter than the follow-up time, which ends when the subjects test is positive.

They are two types of Censoring; Right censoring and Left censoring.