In short: Most organizations already hold enough to show whether a program is working, and the first task is telling outputs and outcomes apart.
You already have more data than you think. These pages cover reading what you have, what to do with years of survey folders, and turning existing information into decisions.
Organizations often have more workforce data than they know what to do with. Before collecting more, get clear about what problem you are trying to solve and what you need to know to make a change that matters.
A grant evaluation runs across the whole award, from the first question asked to the funder's annual report, and the plan can change when the program does.
Working with an evaluator follows a known rhythm, and a good one starts from the records you already keep without judging the state they're in.