Set Active/inactive flag column

Hello!

I have a date table and fact table in my cube where I have period wise project wise finance data. My project number is of text format since it gets values like (301-19, 301-20). I need to set up a flag (Calculated column) Active/Inactive for project based on the value of one column called Turnover. The condition is if there is a change (+/-) in the Turnover value for a project for last 3 months then the set the project as Active else set it Inactive. How can I write the condition?

Regards

PV