The actual hard part
Agreeing on the definitions is harder than building the system.
The hard part is getting sales, finance, and operations to agree on what counts
as a customer, or when an account stops being active. Each department has an
answer that is correct for its own work. The disagreement only becomes visible
when the numbers meet.
So we treat that argument as part of the job, not an interruption to it. We get each
definition stated, tested against real rows, and signed off by the people who own
it. Then it is encoded exactly once, in the database, where every report reads it.
When a definition changes, it changes in one place, and the change is recorded.
If your teams cannot agree on what active means, the dashboard was never the
problem. The definition is. That is where we start.