In my experience, disagreement about priorities is generally not a prioritization problem per se, but rather a strategy one.
What I mean by this is typically disagreement ensues as a result of misalignment. Misalignment is generally caused by a lack of clarity or agreeance on a common direction.
Some common scenarios I see in organizations I coach - either a) their product strategy is missing causing misalignment between the day-to-day work and the organization goals/strategy, or b) the organization strategy is vague or missing leading to misalignment between the different departments as they all set competing goals/strategies/priorities.
Poor strategy or lack-thereof turns prioritization into ‘fair game’, one without boundaries where often the HIPPO effect108 and those who are the loudest wins. This is why clarity on what you are doing and why147 as a first step is so important because without it prioritization is hugely subjective.
So rather than trying to use data or research to form alignment, I'd go back to the root cause by returning to strategy and alignment.
As many attribute Albert Einstein to saying, “If I had an hour to solve a problem I’d spend 55 minutes thinking about the problem and five minutes thinking about solutions.” - this is the same for this problem, rather than spending an hour trying to convince and align others, spend the first 55 minutes ensuring you're all aligned on the goals and strategy.
What might this look like:
- First step is to find common ground (or create it). Begin with discussing what the strategy and common direction is - do we agree at least on that? If not, why not and how might you resolve that to form agreement. If you don't have a strategy, create one!
- Once you've found common ground and created alignment on the strategy and direction then priorities should become much clearer. If you still find yourself in disagreement, look to unearth the assumptions that each party are making. You can do this by taking turns or by doing an exercise like assumptions mapping98. You will find that some assumptions you all agree on, whilst others you do not - focus on those you do not and look to at least agree on an action/experiment* you can do to test that assumption.
- Repeat until you have shifted enough assumptions to a common ground that you are all aligned.
You'll also find that often just talking about it can help resolve any disagreement, simply hearing each other's perspectives and discussing can help generate alignment and you may not need to do step 3.
*Another option for step 2 is to agree on a mitigation or 'line in the sand' where they will be happy to move forward with a direction given that we will come back and revisit that assumption at a later date.