It's tough. I don't envy you your job, honestly. My job is much easier. I get a dollar, I have to give back three. It's very clear.
In my experience so far on this subject, a lot of statistical wrangling goes on. We created these jobs, we're claiming attribution for this, and so the IRR calculation is very fuzzy. I don't have a clear answer, other than putting emphasis on the process, and auditing that process at the end of the day.