| Visualizing data quality and illegibility patterns over time · Published: August 25, 2025

Data Quality Analysis

This visualization shows the data quality patterns for Bills of Mortality records by parish and week. You can examine either illegible records (difficult to read or transcribe) or missing records (incomplete data) to understand temporal and geographic patterns in data quality issues.

Data Quality by Week

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Color Legend: ■ Good (no data quality issues), ■ Partial Issues (some records have issues), ■ All Issues (all records have issues), ■ No Data (no records available).
This visualization helps identify temporal patterns in data quality, which may correspond to different scribes, paper quality issues, or historical events affecting record-keeping. The number of records refers to whether one of the "buried" values or "plague" values or both are missing for a given parish. The data updates regularly as new transcriptions are added to the database.

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Suggested citation

Please use the following as a suggested citation:

Jason Heppler, “Data Quality Analysis,” Death by Numbers, Roy Rosenzweig Center for History and New Media, George Mason University (2025): https://deathbynumbers.org/visualizations/data-quality/.