"Attempting to find the high-risk expenses manually across thousands of expense reports can be frustrating for auditors," said the report. "This is especially true if the organization cannot afford the reputational downside of certain types of spend being hidden away in employee expense reports. If reviewing all high-risk spend is a requirement, the math does not work in auditors’ favor: Sampling only 10 percent of spend when only 10 percent of expenses are high-risk yields a near-zero probability (5.7769042e-14, to be exact) that auditors will find all high-risk spend."