Praxis Data Lab · Variable History

Variable history and harmonization report.

Review variable definitions, cycle chronology, survey design, laboratory methods, method-change boundaries, detection limits, and evidence-backed harmonization actions.

0matching variable codes

0 release records across 0 datasets and 0 cycles.

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Search scope

Filtered NHANES variable history

Cycle: 2025-2026.

Harmonization summary

0 label-stable codes

Label changes detected: 0
Multiple dataset contexts: 0
Unique codes: 0
Enriched codes in this report: 0

Scientific safeguard

Qualified assessment is authoritative; chronology remains supporting evidence.

Praxis separates source-stated method or instrument changes from automated differences in CDC/NCHS method text. The qualified harmonization assessment below is the researcher-facing conclusion; method chronology explains the underlying evidence and does not override that adjudication.

Variable-by-variable chronology

Qualified harmonization assessment and indexed evidence

Each variable first shows the current qualified assessment used by Study Builder, followed by cycle-specific source evidence and method chronology.