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The Data Detective

Why Sales Dropped by 18% (And It Wasn't Sales)

A forensic walkthrough of a KPI panic that turned out to be a data pipeline issue — not a commercial problem.

By Nick Seal 10 min read

Executive summary

Sales dropped 18% in the executive dashboard. The cause was a returns classification change in the pipeline — not declining demand.

The email arrived at 08:14 on a Monday. Revenue was down eighteen percent. By 09:00, three VPs had copied in Finance.

Start with the number, not the narrative

Before you explain the business story, trace the metric to its source. Which table, which filter, which definition changed?

Key takeaways

  • Trace KPIs to source before briefing stakeholders
  • Pipeline changes need definition impact analysis
  • Document metric definitions when systems change

Frequently asked questions

How do I investigate a sudden KPI change?

Compare period-over-period at source-table level, then review recent deployments and definition changes.

What tools help trace data lineage?

Use warehouse query history, transformation logs, and a simple source-to-report mapping document.
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Nick Seal

Writer, speaker and data architecture practitioner helping organisations make better decisions.

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