What's a surge? — A product whose Amazon sales rank suddenly jumps — it's selling far faster than its normal pace (rank at least ~2x better than its recent baseline).

Sustain vs fade — Sustain means the product is still ranking at least ~2x above its pre-surge baseline down the road — still selling at the boosted pace, not slid back to its old rank. Fade = it drifts back toward that old rank. Chase a surge blindly and it usually fades: three months on, only about 1 in 5 is still selling this way.

The edge — When we call a KEEPER, about 2 in 5 are still selling three months on — vs the ~1 in 5 you'd get chasing surges blind. That's long enough to source, land, and sell through. The table above shows how those odds slide as your lead time stretches out. DUDS are the opposite call: the ones at the very top of the list (our most confident) fade almost every time. Confidence is why we rank them.

Confidence — How sure we are the call holds — higher means surer, for keepers and duds alike (a 90% dud = we're 90% sure it fades).