Quality Scoring
Design Philosophy
Quality scores are not just "how good is this entry" — they measure trustworthiness for machine learning. An entry might be perfectly valid DFT data but score low on novelty (too many similar entries). This is intentional: a diverse, well-sampled dataset produces better models than one with 100,000 copies of Li₂O.
Score Components
The quality score is a composite of five sub-scores (max 95, normalized to 0-100):
| Sub-score | Max | What it measures |
|---|---|---|
| Geometry | 25 | Structure quality: nsites, volume, density reasonableness |
| DFT | 20 | Property completeness and physical range |
| Metadata | 15 | Space group, density, structure_json presence |
| Novelty | 20 | How unique this entry is relative to the dataset (diversity bonus) |
| Chemical | 15 | Chemical reasonableness (element combinations, valence, etc.) |
Calibration
We proved the quality score is monotonically related to label reliability:
| Score Bin | N | Valid% | SG% | Complete% | FE Out% | FE MAE |
|---|---|---|---|---|---|---|
| 50-60 | 4,807 | 0.1% | 0.1% | 0.0% | 0.31% | — |
| 60-70 | 32,273 | 27.9% | 2.0% | 0.0% | 0.01% | 0.80 |
| 70-80 | 146,001 | 77.4% | 8.8% | 0.1% | 0.00% | 0.23 |
| 80-90 | 83,649 | 85.2% | 97.4% | 82.7% | 0.00% | 0.18 |
Key finding: score 80-90 is research-grade:
- 97.4% have verified space groups
- 0% property outliers
- 0.18 eV/atom cross-source FE MAE (close to DFT noise floor)
Thresholds
| Threshold | Purpose |
|---|---|
| ≥ 70 | Validated tier — basic research use |
| ≥ 80 | Strict Gold — publication-grade, benchmark-ready |
| ≥ 90 | Not yet achieved — reserved for experimentally validated entries |
Score Distribution
50-60: 4,807 (1.8%) ██
60-70: 32,273 (12.1%) ████████████
70-80: 146,001 (54.7%) ████████████████████████████████████████████████
80-90: 83,649 (31.4%) ████████████████████████
90-100: 0 (0.0%)
Sub-score Means
| Sub-score | Mean | Max |
|---|---|---|
| Geometry | 16.7 | 25 |
| DFT | 19.7 | 20 |
| Metadata | 11.8 | 15 |
| Novelty | 14.2 | 20 |
| Chemical | 15.0 | 15 |
Limitations
- No score ≥ 90 — scoring is conservative; no entry has "perfect" metadata
- OQMD entries score lower on metadata (missing space group until computed)
- Novelty scoring may unfairly penalize common structures