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Praxis Data Lab

Praxis Data Lab · Study Builder

Build your NHANES study with harmonization intelligence.

Combine variables from the indexed Continuous NHANES catalog, choose the cycles you need, and see how Praxis connects source history, methods, cycle boundaries, and cross-code lineage into a study-specific harmonization view.

3variables selected
Praxis harmonization guidance available

Praxis found harmonization conditions for this study and has surfaced them below with the supporting source evidence.

3 variable assessments

ARXO2WD
Evidence developinglow confidence

Examination

OCCIPUT-TO-WALL DISTANCE IN CENTIMETERS

Source releases
1
Available cycles
2009-2010
Dataset
Arthritis Body Measures

No normalized longitudinal change evidence is available for this variable. Absence of events must not be interpreted as proof of cross-cycle equivalence.

Evidence provenance: Praxis automated inference from indexed CDC/NCHS evidence

Remove from studyVariable historyCDC source
AUDLOABC
Compatible with harmonizationmoderate confidence

Examination

Other Exam Abnormality, Left, Comment

Source releases
10
Available cycles
1999-2000 · 2001-2002 · 2003-2004 · 2005-2006 · 2007-2008 · 2009-2010 · 2011-2012 · 2015-2016 · 2017-2018 · 2017-2020
Dataset
Audiometry

No blocking method discontinuity is identified inside the selected cycle span, but one or more longitudinal changes require explicit harmonization conditions before pooling.

Evidence provenance: Praxis automated inference from indexed CDC/NCHS evidence

Evidence signals: source-derived · automated-difference

Relevant boundaries: 1999-2000 → 2001-2002 · 2001-2002 → 2003-2004 · 2003-2004 → 2005-2006 · 2005-2006 → 2007-2008 · 2007-2008 → 2009-2010 · 2009-2010 → 2011-2012 · 2011-2012 → 2015-2016 · 2015-2016 → 2017-2018 · 2017-2018 → 2017-2020

Praxis harmonization actions
  • Verify merge grain, companion variables, and component-specific analytic guidance for the new file context.
  • Select the weight appropriate to each cycle and subsample; when pooling cycles, construct the combined weight according to NHANES guidance rather than reusing a single-cycle weight unchanged.
  • Review the adjacent codebooks/methods. Keep this boundary as documentation variation unless source evidence confirms a substantive method or instrument change.
  • Confirm that the construct and coding are unchanged before pooling or recoding.
  • Apply cycle-specific eligibility rules and restrict the pooled analytic population to a defensible common target population.
Supporting CDC/NCHS evidence
Remove from studyVariable historyCDC source
BMXWT
Compatiblehigh confidence

Examination

Weight (kg)

Source releases
12
Available cycles
1999-2000 · 2001-2002 · 2003-2004 · 2005-2006 · 2007-2008 · 2009-2010 · 2011-2012 · 2013-2014 · 2015-2016 · 2017-2018 · 2017-2020 · 2021-2023
Dataset
Body Measures

CDC/NCHS documentation supports continuity of the core NHANES anthropometry protocol across Continuous NHANES. Indexed differences for body weight are limited to dataset context and documentation wording, not a confirmed measurement discontinuity.

Evidence provenance: CDC/NCHS source-confirmed evidence · Praxis deterministic adjudication

Evidence signals: source-stated

Praxis harmonization actions
  • Pool body weight across calibrated cycles without a method adjustment when no substantive variable-level change is present. Review weight comment codes, amputation handling, pregnancy considerations, and cycle-appropriate survey weights.
Supporting CDC/NCHS evidence
Remove from studyVariable historyCDC source