Study Day Range

**Semantic type:** Temporal Concept

**Definition:** The relative timing for a planned or performed activity expressed as the number of days offset from the study-defined reference activity (e.g., date of registration, start of treatment) for this particular experimental unit. EXAMPLE(S): Day 1, Days 10-20 OTHER NAME(S): Study Day NOTE(S): The study-defined reference activity can be different from study to study. The study day for a date after this reference activity is a positive integer calculated as the difference in the two dates + 1. The study day for dates before the reference activity is a negative integer calculated as the difference between the two dates. Note that this means there is no "Day 0."

**Synonyms:** - studyDayRange - studyDayRange