Praxis Data Lab · Study Builder
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.
Praxis found harmonization conditions for this study and has surfaced them below with the supporting source evidence.
4 variable assessments
Laboratory
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
Examination
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
Demographics
RIDAGEYR remains age in years at screening, but CDC/NCHS changed the public-use disclosure top-code from 85 years and older through 2005-2006 to 80 years and older beginning in 2007-2008. The construct is continuous, but exact values in the oldest ages are not directly comparable across that disclosure boundary.
Evidence provenance: CDC/NCHS source-confirmed evidence · Praxis deterministic adjudication
Evidence signals: source-stated
Relevant boundaries: 2005-2006 → 2007-2008
Demographics
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 → 2013-2014 · 2013-2014 → 2015-2016 · 2015-2016 → 2017-2018 · 2017-2018 → 2017-2020 · 2017-2020 → 2021-2023