Q: What does a zero or empty value in the quantity field mean?
A: In practice, the null and zero values for quantity have the same meaning. They come from the non-reported data (null) or the estimation method (zero). In the original data sources (customs data or enterprise survey), some quantity information may be missing, resulting in a data gap. This does not happen for the value measure. You can learn the estimation methodology at Quantity and Weight Data in UN Comtrade.
Q: Can I sum quantity values, including zero or null?
A: Caution is required when summing quantity data:
- Avoid summing when any data point is zero or null, which may lead to misleading totals. Some tools might ignore these values, resulting in inaccurate aggregation.
- Ensure quantity units are consistent before summing. Mixing different units (e.g., kilograms and number of vehicles) results in meaningless totals.
- Do not aggregate across incompatible commodities. Summing quantities like “number of chickens” and “number of cars” is invalid due to unit and category differences.
- Use judgment when aggregating weight-based units. While detailed commodity-level aggregation may be problematic, summing weights at a higher level can be useful for applications like infrastructure or logistics planning.
