The formula depends on how your report defines a week. Do weeks start at the begin date of the range, the beginning of the month or year, a specific day of the week, or something different? How do you handle fractional weeks when you "roll over" the week counter (for example one ISO standard allows partial weeks at the beginning and end of a year, another ISO standard allows the first week of the year to start in the prior year).
Originally Posted by jj2
In theory, theory and practice are identical. In practice, theory and practice are unrelated.