Choosing primary data or a default factor

Measured data and default factors have different bases. Make the source, scope and data gaps visible on every calculation line.

24 September 2024Updated 23 September 2026

Short answer

Use primary data when its coverage and quality are adequate, for example when verified against fuel receipts or meter records. For uncovered activity, select a default factor accepted by the method and record its source, version and assumptions. Mark measured and defaulted portions separately so gaps become specific data requests.

Primary data is activity information measured or recorded by the operation; a default factor is a value taken from a defined method. Choose based on which activity and period the data actually covers.

Check the measurement coverage

For sources such as fuel receipts, vehicle logs, distance records or site meters, check which vehicles, trips and dates they include. If vehicles or periods are missing, do not apply the data as though it represents the whole fleet.

Retain the factor source

If primary data is unavailable or its coverage is insufficient, choose a default factor accepted by your method. Keep its source, version, geographic or operational scope and assumptions in the calculation file; label the two data types separately.

For subcontracted trips, include fuel, distance, period and trip-matching fields in the contract or data request. Check the same scope in the next report and replace defaulted portions only with newly verified records.