Activity is the work performed; output is what that work produced; outcome is an observed change in something relevant. “Attended six meetings” describes activity. “Created a form with required fields” describes output. “Incomplete requests fell from 20 of 200 to 16 of 200” describes an observed outcome.
Explain the relationship. The form may have contributed to fewer missing details, but other changes may have happened simultaneously. Saying “the measure declined after the change” differs from proving the change caused the entire decline.
A useful account combines problem, action, output, outcome and limitation: “I identified missing fields, proposed a revision with support and followed two comparable batches. The incompleteness rate fell from 10% to 8%; the team also received guidance, so we did not isolate the form’s effect.”
Not every contribution has a simple number. A documented decision, resolved exception or risk found before implementation can provide evidence when you explain what was observed and who can confirm it. Do not invent a financial value to make the contribution seem important.