count the number of tests analyzed based on patient and date range

[ingeoa88]

Hi, I need to count the number of times a test is analyzed where one should only count cases at 1 month intervals for each patient.
see attached example.

hope someone can help with this. Until now, I have tried the "if" formula, but have not succeeded.

[#2]

Hi @ingeoa88 

I did not undertand why you did not wanted 20.02.2020 to be counted, because that does not follow the pattern. 

The combination Patient ID and month Value would be a Uniq value. And you will only get 11 12 111. Counting teh leftmost value in that dynamyc list will give you the result. 

Best Regards

- Geur