A design function is defensible when it is tied to numbers a board already reads. Everything else is decoration.
Revenue per release, conversion, support-ticket volume, rework hours. Pick two, baseline them, and report movement quarterly.
Choosing the numbers
The metric must belong to the business, not to design. NPS is weaker than repeat purchase. Usability scores are weaker than support cost.
Design budgets survive planning season when they arrive attached to a P&L line.
Reporting rhythm
One page, once a quarter, same format every time. The discipline is the credibility.
This essay draws on the open dataset. Add your numbers to it.
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