Data quality · 3 short notes
Check the data behind the chart
A precise-looking chart can rely on uneven histories. Source, freshness, price basis, and missing observations belong beside the result.
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Field note 1 of 3
Name the source and the date
Identify the provider and the latest observation date. Keep that as-of date separate from when the data was retrieved; a recent download can contain an older market observation.
Source date and retrieval time answer different questions.
Field note 2 of 3
Check coverage for each holding
Compare the requested window with the usable dates for every instrument. A portfolio-level summary can hide a short or interrupted history in one sleeve.
Illustration: the shared dates are narrower when one series has gaps.
Field note 3 of 3
A caveat narrows the claim
Price basis, missing-data rules, and assumptions shape what the calculation can support. Quality metadata makes those limits visible; it does not fill gaps in the evidence.
Keep observed data, calculated summaries, and modeled overlays distinct.
Source
Guide: Portfolio data quality. The source describes provenance, freshness, common coverage, price basis, and missing observations.
Evidence boundary
Quality notes help explain the limits of selected observations; they do not make incomplete history complete or remove market uncertainty. A recent retrieval time is not the same as a recent market observation.
Quality notes help explain the limits of selected observations; they do not make incomplete history complete or remove market uncertainty. A recent retrieval time is not the same as a recent market observation.