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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

  1. No score ≥ 90 — scoring is conservative; no entry has "perfect" metadata
  2. OQMD entries score lower on metadata (missing space group until computed)
  3. Novelty scoring may unfairly penalize common structures