Cognos Dashboard: create a query from two data sets

This is simple enough to do in a Cognos report, but I want to do it in a Cognos dashboard.

I have data from two data sets, last month and this month, that may look like this:

LastMonth

ThisMonth

I want a visualization (list, table, scorecard, etc.) to present the changes by category. I want to know how much of the total change was attributed to accounts leaving, accounts being created, and how much of it was within ongoing accounts.

Output

Is it possible to do this within the dashboard, or will I need to develop some upstream object (data set or module) to make this happen?

Without knowing the source of the data sets and their nature etc. it would be difficult to recommend much more specific than this.

You might need to model what you want in a module.

You would need to normalize the dimensions and facts so that the objects in your data sets resemble a star schema. This would be done by some combination of modelling tables from your sources and or modelling column dependency.

I was able to use column dependency to munge together two xls files which both had dimension and fact data. The difficult part was modelling the relationship between the tables.

This might be second best.

I'm assuming that the data sets are the things which Cognos calls data sets.

If the data sets are from the same FM model then is it possible to create one data set which combines the objects used to create the two data sets?

It might be better that way rather than re-modelling what has already been modelled.