2.4. Observation Periods
The observation periods were the sum of individually calculated, de-identified subject data for each group. The individual intervention subjects’ observation period began on their date of first dose (plus sixty days) or the date their insurance coverage began, whichever was later; their observation period ended on the date of their last dose or the date their insurance coverage was terminated, whichever was earlier.The individual control subjects’ observation periods began on the date of the first Sixty days were added to the date of first dose of vitamin D3 for the intervention group subjects as this is the time period known to achieve therapeutic vitamin D blood levels [