Decision spectrum is a participatory decision model developed by Jim Highsmith, you can read more about it from the Edward designer blog (for some reason the forum is not allowing me to post links)
Sometimes the PMP exam will source its questions from materials outside of PMBOK, although it does not happen often (I had 2 questions like that in my exam)
I had a quiz question where the correct answer was Decision spectrum. I don't recall learning that. What video or other material covers this information ?
Training for Project Management Professional (PMP)®, PMI Agile Certified Practitioner (PMI-ACP)®, and Certified Associate in Project Management (CAPM)®