How the selection works
These are five distinct catalog listings in the stated category, initially ordered by title. Use title and brand controls to change the order. Position is not a quality rank. Every product shows a published editorial rating calculated from its stored listing documentation. because no independent comparative performance measurements support a numerical rating.
Manufacturer documentation and exact listing details answer different questions. A seller title identifies the listing but does not prove dimensions, performance or accessory compatibility. We do not award best value without verified prices.
Where the exact Amazon listing title or feature bullets state them, our documented spec-fit score for a full-body massage chair is 100 × [0.35 × mechanism (4D stated = 1, 3D stated = 0.7, otherwise 0.35) + 0.25 × (zero-gravity recline stated ? 1 : 0) + 0.20 × roller track (SL-track stated = 1, L-track = 0.7, S-track = 0.4, none stated = 0) + 0.20 × (a heat function stated ? 1 : 0)], rounded to a whole number. A term the listing does not state contributes its minimum — nothing is ever inferred from photos, brand reputation or similar models. This index reflects how the seller documents the listing; it is not measured motion quality, not comfort, and not a customer review.
Massage guns, foot and leg massagers, seat and back massagers and accessories use a documentation completeness score: 100 × [0.5 × min(documented feature bullets / 8, 1) + 0.3 × min(product images / 5, 1) + 0.2 × (brand documented ? 1 : 0)], rounded to a whole number. Every input is read from the stored Amazon listing record, so the same listing always produces the same score. It measures how completely a listing is documented — not performance, quality or customer satisfaction.
Where Amazon publicly displays customer reviews for a listing (average star rating and review count captured from the public product page), the raw editorial score is 100 × [0.45 × (Amazon average / 5) × min(review count / 50, 1) + 0.35 × min(log10(1 + review count) / log10(1 + 5000), 1) + 0.20 × documentation score / 100]. The confidence factor min(review count / 50, 1) damps averages based on very few reviews, and the logarithmic volume term rewards large public review volumes, so widely and highly reviewed listings rank ahead of thinly reviewed ones. Listings with no captured public review data use the documentation score alone. This combined index reflects the public Amazon reputation and the listing documentation — it is not a physical test and not our own product testing.
Raw documentation scores are normalized across our full catalog to a 5.1–9.9 editorial display scale; ranking order always follows the raw documented score. The displayed value is an editorial index of listing documentation — not a physical test result and not a customer review.
