# How do I calculate time between events?

Endpoint and detailed longitudinal data in DF12 contains approximated event date APPROX\_EVENT\_DAY, which is random (up to +/-15 day) offset added for the exact dates for each participant (see [Data masking/blurring of visit dates](/finngen-data-specifics/finnish-health-registers-and-medical-coding/data-masking-blurring-of-visit-dates.md)). In this way you can calculate exact time between events and also compare the temporal order of events between different registers for each individual participant (see [Is there really no participant birth year data in Sandbox?](/faq/about-finngen-data/is-there-really-no-participant-birth-year-data-in-sandbox.md)). In DF12 also EVENT\_AGEs contains 3-digits, in which way you can quite accurately calculate time between events.


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