Calculating HPPD

I just became the assistant clinical manager for our Women's Health Care Department. The department consist of L&D, Level 1 Nursery and a Women's Health care unit. We just had consultants come into the hospital and decreased our HPPD. I was just wondering how other hospitals calculate their HPPD. I am totally new to management and would like to know how to calculate the HPPD on my own and not use what the consultants gave us.

Thanks