Methodology
Every FilterScored score is deterministic and auditable. Each sub-score is the clamped sum of visible score-events - one rule firing on one verifiable input, each carrying an evidence tier and a plain-English explanation you can read on the scorecard. AI parses spec sheets and certification databases; AI does not decide the score.
Evidence tiers
- A - independent certification (NSF, WQA, IAPMO, AHAM, CARB, Energy Star) or accredited-lab test. The only tier that earns certification credit.
- B - published manufacturer spec or recognized industry standard.
- C - heuristic or inferred. Low weight, never decisive.
- Seed - prototype value during build, labeled, replaced by A/B as verification completes.
Non-negotiables
- A claim is not a certification. "Tested to NSF standards" earns zero certification credit and is labeled uncertified.
- Total cost of ownership is computed from real, sourced filter prices. Missing data is a labeled gap, not an estimate.
- Hard fails (ozone generators, uncertified lead/PFAS claims, overstated room sizes) cap a dimension and stay visible in the breakdown.
- Affiliate revenue never moves a score.
Air Purifier v1.0
| Dimension | Weight | Measures |
|---|---|---|
| Verified Performance | 30% | AHAM CADR, true sealed HEPA, air changes per hour, honest room-size match. |
| Total Cost of Ownership | 25% | Computed annual filter cost vs the room-size class median. The number nobody surfaces. |
| Certification | 15% | AHAM Verifide, Energy Star, CARB, published lab efficiency. |
| Safety | 15% | Ozone and ionizer behavior. Ozone generators hard-fail. |
| Practical Fit | 15% | Noise, filter-change indicator, energy draw. Smart features are neutral. |
Water Filter v1.0
| Dimension | Weight | Measures |
|---|---|---|
| Verified Contaminant Reduction | 35% | Held NSF/WQA/IAPMO certifications for the contaminants that matter. A claim is not a certification. |
| Total Cost of Ownership | 25% | Computed cost per gallon vs the format-class median. The number nobody surfaces. |
| Certification Independence | 15% | Certified on the official database vs self-claimed 'tested to' marketing. |
| Capacity & Flow Fit | 15% | Cartridge life and flow appropriate to the format. |
| Practical Fit | 10% | Install, footprint, and source-water readiness. |
Bands
Excellent 8.5-10 · Strong 7.5-8.4 · Mixed 6.5-7.4 · Limited under 6.5. We never publish a composite without its sub-scores.
Related reading
- Tested to vs certified to - why a claim is not a certification.
- Why premium air purifiers score lower - how this methodology treats IQAir, Molekule, and Dyson.
- CADR explained and HEPA vs HEPA-type.