What is a pop report for graded cards?

A pop report, short for population report, is a grading company's published count of how many copies of each card it has graded, broken down by grade. "Pop 1" means the grader has given that grade to only one copy of that card.

It's a useful number with real limits. Each grader counts only its own slabs, so PSA and CGC numbers for the same card differ. And a pop report counts graded copies, not every copy printed: CGC itself warns that its counts don't indicate rarity.

Before you buy one

• Check the count yourself. "Low pop", "pop 1" and "only 2 higher" show up in titles as selling points. Look the card up on the grader's site on the day you buy, and note how many copies sit at grades above the one you're buying.

• Expect the number to move. Counts change as more copies are graded, fastest for new sets, so a number quoted in a listing may be out of date. Look it up again rather than trusting the title.

• Be ready to sign in. PSA's report may ask you to sign in, while CGC's has been open to anyone, so have your PSA login handy.

A ChaseBoard graded watch matches the grader and grade in a listing title and ignores pop claims like "pop 1", so when an alert comes in, look the count up on the grader's site yourself.