what is "censorship" as defined in that study? Example in context: ". Right-censorship was applied in three cases: if the animal was (1) transferred to another

what is "censorship" as defined in that study? Example in context: ". Right-censorship was applied in three cases: if the animal was (1) transferred to another collection, with the date of transfer considered as the censorship event; (2) euthanized for research purposes when still healthy, with the date of sacrifice as the censorship event; or (3) still alive when the process of compiling records was completed, with the date of completion as the censorship event (see Materials and methods)."