# Grade population

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**Grade population:** How many items a grading company has certified at each grade.

## How we measure it

We record the published population count for each item, grade and grading company, with the date.

## What it is not

A low population means few graded copies, not necessarily few copies in existence.

## Where it appears in the data

Field names as the API returns them; each dataset's page in the API lists the field's type and unit.

- `population_count` in dataset `ccg_population`

## Related

- [Trading card sale prices: how we collect them](/methodology/trading-cards/)
- [All glossary terms](/glossary/)