How to compare current and previous data in OTBI?

Hi All,
We have a requirement where we need to fetch and compare the data (an attribute on employee assignment page, say Job or Position) on 2 different dates in OTBI and then keep a counter as well.

For example, with the perspective of a Department 'Sales', how many employees from a particular date to current date have been transferred into the Department 'Sales' and how many have been transferred out of Department 'Sales' (say from 1st Jan to 31st March ).

For this we need to compare employee assignments on 2 particular dates, in OTBI how may we achieve that? (somewhat similar to lag and lead in BIP)