About CensoringTypes
Censoring (Penyensoran): When the exact survival time is not fully observed—only partial information is available.
Right Censoring
Event time is beyond a certain point.
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Type I (Time Censoring): Study ends at a pre-determined time .
- Fixed: All subjects stop at the same time
- Progressive: Different fixed censoring times assigned at start
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Type II (Failure Censoring): Study ends when events occur among subjects.
- Simple: Stops at the -th failure
- Progressive: Some survivors removed at intermediate event times
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Competing Risk: Multiple event types; one event prevents observation of others.
Left Censoring
Event occurred before study started but exact time unknown.
Interval Censoring
Event known to occur within an interval .
Double Censoring
Dataset contains both left-censored and right-censored observations.
Examples
Right Censoring, Type I (Fixed Time)
Clinical Trial: 30 patients treated for heart disease, observed for 6 years. Only 10 had strokes during the study. The other 20 are right-censored (type I) — we know they survived at least 6 years but don’t know when (or if) they will have a stroke.
Right Censoring, Type II (Failure Count)
Carcinogen Study: 40 mice injected with carcinogen, observed until 25 show disease symptoms. The remaining 15 mice are right-censored (type II) — they may develop disease later but we stopped before observing it.
Left Censoring + Right Censoring (Double Censoring)
Survey: Children asked when they started using gadgets. Some cannot remember exact time (left-censored), some started during the study (observed), some haven’t started yet (right-censored).
Comparison with Truncation
| Feature | Censoring | Truncation |
|---|---|---|
| Nature | Missing information about exact time | Selection bias by study design |
| Awareness | Researcher knows subject exists | Researcher may not know excluded subjects exist |
| Likelihood | Uses for events, for censored | Uses conditional probabilities |