The star scores on CatTech Hub are computed automatically from each product's public specifications, using a transparent editorial rubric — not a single store's average rating or a count of verified purchase reviews.
For each category we define the dimensions that matter (for air purifiers: CADR cleaning power, room coverage, quietness, HEPA, and so on) and assign each a weight. Every dimension is scored 0–10 from the actual specs, weighted into an overall score (C = 0–1), and mapped to stars = 3.0 + 2.0 × C (a 3.0–5.0 range). The same specs always yield the same result, and every product page shows the per-dimension breakdown.
This rating measures breadth of capability. A specialized standout (for example, a microchip-controlled feeder) can therefore score lower simply because it omits general features like a camera or large hopper. Please read each product's pros, cons, and fit for your needs alongside the number.
Some metrics are published differently by different makers. For air purifiers, for instance, overseas brands publish CADR while Japanese brands (Sharp, Daikin, and others) state a recommended room area instead. In that case we score the room area as an equivalent proxy for CADR — the two correlate strongly — and we keep the displayed specs exactly as each maker publishes them (we never invent a CADR figure).
Price is not part of the rating. Instead, price appeal is shown separately as a 'value' tier based on capability-per-yen within the same category (great value / fair value / premium price).
The price figures themselves are approximate and change over time — check the store links for the latest price. Over time we plan to fold in even more objective data, such as aggregated reviews and price feeds.