Quick answer
Population reports show how many copies of a card have been graded at each grade. They are one of the most useful tools for Pokémon collectors, but they only tell part of the price story.
Population is not the same as rarity
A low population can mean a card is rare, unpopular, too cheap to grade, or still sitting raw in collections. Always combine pop data with sales volume and demand.
Gem rate matters
If many submitted copies become PSA 10s, the card may be easier to gem than buyers assume. A low gem rate can support a stronger PSA 10 premium when demand is real.
Watch population growth
Fast-growing populations can pressure prices if demand does not keep pace. This is especially important for modern cards returning from large grading backlogs.
Compare grades, not just totals
A card with a high total population but very few PSA 10s can still have a scarce top-grade market. Conversely, a card with thousands of PSA 10s may need massive demand to sustain a premium.
Quick rule
Use pop reports to measure supply risk, then use sold listings to confirm whether buyers still care.