Page Last Updated: November 6, 2025
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). The metadata for studies released via the NBDC Data Hub consists of:
- Data dictionary: Provides detailed information about table variables, including variable name, label, description, data type, etc.
- Levels table: Provides information about the levels for categorical variables (label, order, etc.)
See the following sections for detailed descriptions for each column in the data dictionary and levels table.
Data Dictionary Columns🔗
= Values do not vary across releases
| NAME | LABEL | DESCRIPTION & POSSIBLE/EXAMPLE VALUES |
|---|---|---|
study |
Study | Part of core (Core) or substudy (Substudy) |
domain |
Domain | Domains include: Behavior/Child-Caregiver Interaction | BioSpecimens | Neurocognition & Language | Novel Tech | Physical Health | Pregnancy/Exposure Including Substance | Social and Environmental Determinants | Tabular EEG | Tabular Imaging |
sub_domain |
Subdomain | Domain subcategory (e.g. Structural MRI within the Imaging domain) |
metric |
Metric | Imaging & EEG only: Specific metric assessed (e.g. Cortical Thickness) |
atlas |
Atlas | Imaging only: Atlas used to derive parcellated structural measures and functional timeseries (e.g., Gordon - see full list) |
source |
Source | Source of information. Source values include: Biological Mother | Caregiver (Responsible Adult) | Child | General |
table_name |
Table name | Coded table name, e.g. sed_bm_demo |
table_label |
Table label | Label for coded table name (e.g. Demographics) |
name |
Variable name | Coded variable name within a table (e.g. sed_bm_demo_edu_001) |
label |
Variable label | Label for coded variable name (e.g. Highest grade completed) |
instruction |
Instruction |
Instructions preceding measure questions (e.g. The next set of questions is about your child's behavior...) CAUTION: Instruction text may be incomplete or misaligned! See known issue |
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. m, cm², lbs) |
type_var |
Variable type | Variable types include: administrative | item | derived item | summary score See Variable Type Definitions below |
type_data |
Data type | Data types include: date | timestamp| time | characterOnly used for categorical columns | text | integer | double |
type_level |
Level of measurement | Levels include: nominal | ordinal | interval | ratio |
type_field |
Field type | Field type in data capture system as presented to participant (e.g. dropdown, radio, checkbox, etc.) |
order_display |
Display order | Display order of item within measure |
branching_logic |
Branching logic | Branching logic applied to variable/question |
label_es |
Label (Spanish) | Label in Spanish |
instruction_es |
Instruction (Spanish) | Instruction text in Spanish |
header_es |
Header (Spanish) | Header text in Spanish |
note_es |
Note (Spanish) | Note text in Spanish |
identifier_column |
Identifier column(s) | Columns used for participant identification (i.e. participant & session ID) - see Table Organization for details |
url_table |
Documentation (table) | Link to documentation page |
url_table_warn_use |
Responsible Use Warning (table) |
Responsible use warning |
url_warn_use |
Responsible Use Warning (variable) |
Responsible use warning specific to variable within a table |
url_table_warn_data |
Data Warning (table) | Data warning |
url_warn_data |
Data Warning (variable) | Data warning specific to variable within a table |
order_sort |
Sort order | Standard sort order in table/measure (and column order in database) |
Additional Information🔗
| 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 |
Blank Columns in NBDC Data Access Platform Query Tool
Query Tool searches within the NBDC Data Access Platform currently display columns that are not applicable to HBCD study data, including columns ending with nda, deap, and redcap. Inapplicable columns will be removed in the future and can safely be ignored. Note that columns may also be blank if they have yet to be populated (currently the case for sub_domain, atlas, and metric for example). For reference, only applicable columns are included in the Data Dictionary overview above.
Additional Columns ('cohort' & 'site') Not Defined in Data Dictionary
Dataset downloads contain 2 additional columns not described in the data dictionary. This includes cohort and site, identical to Visit Information variables par_visit_data_<cohort|site>.
Levels Table🔗
= Values do not vary across releases
| Name | JSON Element | Description |
|---|---|---|
name |
Name of the categorical column/variable/question for which value/label pairs are reported | |
value |
left hand side | Value of the level (e.g. "1") |
order_level |
Order of response option as displayed to participants (and in data) (e.g. "2") | |
label |
right hand side | Label of the level (e.g. "Yes") |
label_es |
Label of the level (Spanish) (e.g. "Si") |