A survey period is part of a dataset’s identity. For NHANES 2017–March 2020, shortening the label can conceal why the release was constructed differently. Keep the full period and its analytic guidance with any source note.
CDC’s overview explains that March 2020 fieldwork suspension left the 2019–2020 cycle incomplete. The partial data alone were not nationally representative. CDC combined them with 2017–2018 data using additional weighting procedures to create the named prepandemic files.
Identify the exact release
Record the file name, complete period label, variable documentation and guidance used. Distinguish a source downloaded for the combined period from an ordinary two-year-cycle file. An access date does not replace the observation-period label.
If an inherited analysis folder contains several releases, preserve which file supplied each variable. Do not select a similarly named file merely because it opens successfully or contains a familiar participant identifier.
Keep method decisions traceable
A note should identify the analysis population and the guidance consulted for weights and design variables. This article provides no substitute weighting formula. A technical analysis needs the relevant official documentation and appropriate statistical expertise.
When a previous result is being updated, compare the defined periods and methods before describing a change as a population trend. A different file structure or period can create a comparability question that needs to be resolved explicitly.
Write a source line that preserves the exception
Name the combined prepandemic release rather than compressing it into an ordinary 2019–2020 observation. Where a brief cannot explain the full design, it can still retain the period and point readers to the exact guidance used.
The CDC overview read for this guide is historical guidance first published in May 2021, not a new survey announcement. No survey outcomes or national estimates were computed here. The task is reliable dataset identification, without interpreting anyone’s health or recommending a diet.
Official source documentation read 21 October 2026. The worksheets are editorial reading aids; no population result, individual diagnosis or clinical recommendation is supplied.
Sources: Official indicator or dataset documentation. Related discussion: health information source quality.
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