The result of preventive service may be that no incident occurs; that observation alone does not prove an investment's effect. Comparable records show what work was done and which outcomes were tracked.

Fix the scope first

State route, product group, delivery volume and reporting period. Match dispatch lists to delivery times, delays, measurement deviations, returns and complaints. Keep each indicator's definition and data source consistent.

If there is no pre-change data, say so; do not directly compare another route or period. Track labour, service, waste and equipment invoices separately. Assess changes alongside season, volume or process changes.

A concise evidence file for management. Show scope, record period, measured indicators, missing data and actual costs on one page. Do not present expected savings as achieved results. Refresh the investment decision using current supplier quotes and your own operating records.