Data Quality
5 posts on the data-quality checks and instincts that separate senior analysts from juniors.
- Data Quality10 min read
The SQL Data-Quality Checks Senior Analysts Run Before Every Report
The 30-second sweep that catches 80% of "why does this number look weird" bugs before they reach a stakeholder — NULL audits, dedup checks, refund leakage, timezone sanity.
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How to Diagnose a Dashboard That Looks Wrong
A senior analyst’s triage playbook for the Monday morning Slack: "the number on the dashboard doesn’t match Finance — can you check?"
Read the post - Data Quality7 min read
Anti-Joins and the LEFT JOIN ... IS NULL Pattern
Finding what’s missing — the single most-used and most-often-written-wrong pattern in analyst SQL.
Read the post - Data Quality12 min read
Donor Deduplication in SQL: A Practical Playbook
A field-tested SQL playbook for finding duplicate donor records — exact match, normalized match, phonetic codes, Levenshtein, and composite scoring — with the gotchas nonprofits actually hit.
Read the post - Data Quality10 min read
How to Read a Messy Database Like a Senior Analyst
Every production database is a crime scene. Here’s the senior-analyst workflow for reading it: what to profile, what to distrust, and how to sanity-check before you report a number.
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