About project codes

Each project within the NTR has a project code. This code has the format <XX>_<EXTENSION>. The first letter indicates whether the study was conducted in adult participants (ANTR), indicated by the letter A, young twins and their parents (YNTR), indicated by the letter Y, or both (NTR), indicated by the letter N.

The second letter indicates the type of study:

• S (survey)
• E (experimental study)
• A (aggregated/derived variables)
• B (biobanking study)
• I (interview)
• C (combination)
• L (record linkage)
• O (other)

The extension is study specific, so we can distinguish between studies. The extension often contains a number (referring to a wave or age group) and sometimes an addition V or M to indicate father (V for "vader") or mother (M for "moeder") reports.

So for example, YS_1 is the YNTR Survey study in children aged 1; AS_10 is the 10th wave of ANTR surveys; NB_BB1 is the first NTR Biobanking study.