BeBlood — HRIS transformation (Oracle HCM)
Effort estimation by Monte-Carlo simulation at P80, plus a risk register — replacing a single number with a defensible range.
Context
HRIS transformation on Oracle HCM. The question put to the workstream was not "how much does this cost" but "with what confidence can we state that number".
What I did
Effort estimation by Monte-Carlo simulation rather than by summing averages. Each work package is estimated as a range — optimistic, likely, pessimistic — then the model draws thousands of scenarios to produce a distribution of total effort. We report the P80: the effort figure that covers 80% of simulated scenarios.
Alongside it, the workstream risk register: identification, rating, owner and mitigation for each retained risk.
Outcome
A defensible effort range with its confidence level attached, instead of a single number pulled out of a spreadsheet. [TODO: metric] estimated effort and the spread between P50 and P80.
What I took from it
The sum of average estimates is almost always optimistic: it ignores that overruns compound while savings do not. Reporting a P80 rather than a mean changes the conversation with the sponsor — you discuss an accepted level of risk, not a number to negotiate down.