[R] survival analysis sampling question

[array chip]

Hi, not sure if this is the best place to ask this
statistical question, but here it goes:

Does doing survival analysis mandatorily require
consecutively recruited patients? If I have a
retrospective patient sample, but not consecutively
recruited, does it necessitate invalidity of the use
of survival analysis (for example: Kaplan Meier
analysis or Cox regression, etc). Or as long as the
patient sample is a random sample of the population
(though it may be hard to prove that), it will be ok?

Thanks for sharing your thoughts
		
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