NBDC Data Dictionary🔗

Tabulated HBCD study data is organized into a standardized table format per study instrument/measure, with each table containing a set of variables (see Data Structure Overview for details). Metadata is organized via a data dictionary, which provides detailed information about table variables, including variable name, label, description, data type, etc. All data dictionary elements are outlined below.

Data Dictionary Elements🔗

 = Values do not vary across releases    = Column available in Spanish (includes label_es, instruction_es, header_es, note_es)

NAME	LABEL	DESCRIPTION & POSSIBLE/EXAMPLE VALUES
CORE METADATA
study	Study	Part of core (Core) or substudy (Substudy)
domain	Domain	e.g. Demographics- see Instruments by Domain for full list
source	Source	Source of information (Biological Mother; Caregiver (Responsible Adult); Child; General)
IMAGING & EEG
atlas	Atlas	MRI atlas used for parcellated structural measures and functional timeseries (e.g., Gordon)
metric	Metric	Specific metric assessed (e.g. MRI Cortical Thickness)
sub_domain	Subdomain	Domain subcategory (e.g. Structural MRI within the Imaging domain)
TABLE-LEVEL INFORMATION
table_name	Table name	Table name (e.g. sed_bm_demo)
table_label	Table label	Human-readable label for table name (e.g. Demographics)
url_table	Documentation (table)	Link to documentation page
url_table_warn_use	Resp Use Warning (table)	Responsible Use Warning (see details)
url_table_warn_data	Data Warning (table)	Data Warning (see details)
VARIABLE-LEVEL INFORMATION
name	Variable name	Variable name within a table (e.g. sed_bm_demo_edu_001)
description	Variable label	Human-readable label for variable (e.g. Highest grade completed). Alternative name: label
levels	Levels	Embedded tables with Value:Label options for categorical variables
instruction	Instruction	Instructions preceding form items (e.g. The next set of questions is about your child's behavior...)
header	Header	Header/instructions for a set of questions (e.g. For each item that describes your child...)
note	Note	Note displayed to participants (e.g. Enter weight in pounds.)
unit	Unit	Unit of measurement (e.g. years, cm, lbs, etc.)
url_warn_use	Resp Use Warning (var)	Responsible Use Warning (see details) - variable-specific
url_warn_data	Data Warning (var)	Data Warning (see details) - variable-specific
VARIABLE TYPE & FORMAT
type_var	Variable type	Includes: administrative; item; derived item; summary score - see details
type_data	Data type	Includes: date; timestamp; time; characterOnly used for categorical columns; text; integer; double
type_level	Level of measurement	Includes: nominal; ordinal; interval; ratio
DISPLAY PROPERTIES
type_field	Field type	Field type presented to participant (e.g. dropdown, radio, checkbox, etc.)
order_display	Display order	Order in which item is displayed to participants within a given measure
branching_logic	Branching logic	Branching logic applied to variable/question
IDENTIFIERS & ORDER
identifier_column	Identifier column(s)	Columns used for participant identification (i.e. participant & session ID)- see details
order_sort	Sort order	Standard sort order in table/measure (and column order in database)

Variable Types🔗

Variable Type	Description
administrative	Data that gives context to the assessments, e.g. date, language, quality control, etc.
derived item	Derived from original participant data (e.g., combining separate entries for feet and inches into a single derived height variable in inches) - see Basic Demographics for more examples
item	Original data provided by the participant, e.g. questions in a questionnaire
summary score	Summary and/or score output based on algorithmic conversions of items/raw data

Site & Cohort Information🔗

Datasets downloaded from the NBDC Data Access Platform contain two additional fields not listed in the data dictionary, cohort and site. These are derived from the Visit Level Data table variables par_visit_data_cohort and par_visit_data_site.

• cohort: study cohort, e.g. HBCD Main Child vs. HBCD Multiple Birth (see Cohort & Caregiver Types for details)
• site: site where visit occurred (distinct from site at time of recruitment - see recruitment_site in Basic Demographics)