if you allow "year blocks" to overlap, the situation becomes complex. Consider the following admission dates for one patient:
march 07, september 07, october 07, January 08
The pair of admissions in Sept-07 and Oct-07 may be within "year blocks" starting Mar-07 and/or Sep-07. Is this restricted? On what basis?
What if the dates sequence places the 4th closer to the 3rd than the 2nd is to the first. E.G. Jan-07, Nov-07, Dec-07, Jan-08
In that case Nov-07 to Jan-08 looks more of an episode than Jan-07 to Dec-07.
If you want "every year block including 3 admissions", then that will involve overlapping blocks. Is that required? If not, on what basis should there be restriction?
My first example included 4 admissions within 12 months.
Is that treated as one group? When there are, say 9 admissions within 12 months, is that 3 episodes or one?
sorry to start asking questions when you seem to be close to closure 😉
peterC