# Timeline recursion does not skip summaries

The enclosed model contains a timeline (Year/Month). In the “Closing UPR Assumption” matrix, I compute the “Calculation” item using a weighted average of the last twelve “Base” items (the weights are in a matrix called “Closing UPR Rate”). The formula is as follows:

Calculation:Month[THIS] = sumproduct(Base:Month[THIS-11] .. Base:Month[THIS],Closing UPR Rate::Closing UPR Rate%)

The problem is that the “Base:Month[THIS-11] .. Base:Month[THIS]” recursion does not skip the Sum of Months, which is a summary item. The result becomes totally distorted as a consequence.

I would like to recursion to skip the “Sum of Months” items in the Base item row. The recursion should compute using only genuine months.

Is there a way to do this ?

Thanks a lot

FYI if you have the need to do different offsets simultaneously, I would suggest calculating a single index value (that ignores all summary items). That way can support multiple, differently offset data references simultaneously.