= Solution
Choose a common endpoint for the eight-month analysis and ascertain every student's status through that endpoint. With a complete event register, record each departure at its event time and right-censor every remaining student at the same administrative cutoff. Otherwise obtain a confirmation for all students at the cutoff, not just the most recent quarterly list, and verify intervening departure dates consistently.
A second coherent design is to analyse only up to the last common verified quarterly date, postponing a longer analysis until a further complete follow-up round is available. Extra event reports after that date cannot be combined with earlier <censoring> of all nonfailures as though the resulting <risk set> were independently censored. Genuine losses to follow-up should be recorded separately and their possible <informative censoring> assessed. \b[Use a common observation rule for failures and nonfailures, independent of their subsequent outcome.]
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