Whitepaper

40.7 percent: making survey data quality provable

Speeders, straightliners and the GDQ code frame: documenting data cleaning instead of defending it

  • 14 pages
  • 20 min read
  • English
  • Free

What you get

  • The German GDQ figures with definitions, bases and the report's own caveats
  • The GDQ code frame: 18 removal reasons with stage and degree of automation
  • Checks and default thresholds for seven codes, from speeders to duplicates
  • The known false positives: valid straightlining, mobile users, short open ends
  • Flag instead of delete: audit trail, quotas, weighting
  • A cleaning protocol for the method report and twelve self-audit questions

In short

In the GDQ Data Quality Benchmarking, Wave 2, German research agencies remove 40.7 percent of their records before and during the survey, sample suppliers 10.1 percent. The report calls this a striking divide and warns in the same breath against reading removal rates as a league table. What the number shows above all is that every agency cleans differently and hardly any can back its rate with rules, thresholds and case counts, although the quality standards of ADM, ASI, BVM and DGOF have required exactly this documentation since 2023. This whitepaper explains the benchmark figures with their definitions, presents the GDQ code frame with its 18 removal reasons, gives checks, default thresholds and the known false positives for seven of them, and closes with a one-page cleaning protocol for the method report and twelve self-audit questions.

Who it is for
Institutes & agencies · Corporate insights teams
Format
PDF, 14 pages, with worksheets and checklists

Contents 8 chapters

  1. 01 The benchmark: what GDQ Wave 2 measured
  2. 02 Why removal rates cannot be explained today
  3. 03 The GDQ code frame: 18 reasons, one language
  4. 04 The rulebook: seven codes you can check
  5. 05 Flag instead of delete
  6. 06 The one-page cleaning protocol
  7. 07 Self-audit: twelve questions
  8. 08 Where DataLion fits

Download the whitepaper

Dr. Benedikt Köhler

The author

Dr. Benedikt Köhler · Co-founder of HybridAI and CEO of DataLion

Dr. Benedikt Köhler is co-founder of HybridAI and CEO of DataLion. Cognilytica lists him among the top 50 most influential data scientists worldwide. The whitepapers come out of projects with institutes, insights teams and universities.

October 2026

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