Page Last Updated: October 20, 2025

Data Structure Overview🔗

The HBCD dataset follows NBDC data structure standards established as part of the ABCD Study (see details), which incorporates the Brain Imaging Data Structure (BIDS) wherever possible for cross-study consistency. At a high level, data are organized into two categories:

Tabulated Data

Study instrument (behavior, biology, and environment), Demographics, and select file-based data organized in a standardized tabular format that includes all participant data per table.
Go to Tabulated Data documentation

File-Based Data

Unlike tabulated data, file-based data comes in a variety of formats, often modality-specific. File-based data includes:

Raw BIDS Raw imaging, EEG, and biosensor data converted to the BIDS standard with unaltered signal content
Derivatives Processed imaging, EEG, and biosensor datasets generated by standardized pipelines

Go to File-Based Data documentation

Which file-based data are also available as HBCD tabulated data? (Click to expand) â–¸

When possible, tabulated data tables are derived from file-based data (e.g., MRS, MRI, EEG, wearable sensor data) to provide a single file with rows across participants/sessions. Users may choose either the original file-based data or the combined tabulated version, depending on their needs.

Not all processed data are available in tabulated form. Tabulated datasets have one row per participant/session, so only derivatives that can be summarized into a single row/column structure are included. If no tabulated file exists for the derivatives you need, you will need to use the file-based data.

  • Tabulated data: one row per participant/session with summary fields.
  • File-based data: required for complex, multidimensional, or non-row-summarizable outputs.

Note tabulated files closely mirror their source derivative file names for easy cross-reference. For example, the following subject/session-level XCP-D derivatives are combined into a single tabulated file:

File-based derivatives sub-{ID}_ses-{V0X}_task-rest_dir-PA_run-{X}_space-fsLR_seg_Gordon_stat-alff_bold.tsv
Tabulated file img_xcpd_space-fsLR_seg_Gordon_stat-alff_bold.tsv 

hbcd/
|__ derivatives/       # Derivatives
|
|__ rawdata/ 
    |__ phenotype/     # Tabulated Data
    |__ sub-{ID}/      # Raw BIDS
Detailed Folder Tree Summary â–¸ 
hbcd/
|__ derivatives/        # Processed pipeline derivatives
|   |__ bibsnet/
|   |__ hbcd_motion/
|   |__ made/
|   |__ mriqc/
|   |__ nibabies/
|   |__ osprey/
|   |__ qmri_postproc/
|   |__ qsiprep/
|   |__ qsirecon/
|   |__ symri/
|   |__ xcp_d/
|
|__ rawdata/ 
    |__ phenotype/     # Tabulated data (demographics, visit info, behavior, etc.)
    |   |__ par_visit_data.*
    |   |__ sed_basic_demographics.*
    |   |__ {instrument_name}.*
    |
    |__ sub-{ID}/      # Raw BIDS formatted data (MRI, MRS, EEG, biosensors)
    |   |__ sub-{ID}_sessions.tsv
    |   |__ sub-{ID}_sessions.json
    |   |__ ses-<V0X>/
    |       |__ anat/
    |       |__ dwi/
    |       |__ eeg/
    |       |__ fmap/
    |       |__ func/
    |       |__ motion/
    |       |__ mrs/
    |       |__ sub-{ID}_ses-<V0X>_scans.tsv
    |       |__ sub-{ID}_ses-<V0X>_scans.json
    |
    |__ dataset_description.json
    |__ participants.tsv
    |__ participants.json