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title: "Standard variable naming in longitudinal projects"
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::: callout-note
## Under development

Objectives:
- Check existing standards and principles used by, for example, the IEA, OECD and Statistics Norway.

:::


Although there is no compulsion, there are great advantages over time if the variables are named in a systematic way so that you can later create a pattern for which variables are the same over time, which have changed somewhat but approximately the same, etc. This enables trend displays.

# General advice

- Use English as far as possible
- Underline to separate words, not lower/uppercase letters. But numbers vs letters can make a difference
- Avoid years. A survey can last over the New Year. Is it the year of publication, data acquisition, or the "litter" you have indicated?!...
- Use either cycle numbering, or preferably cohort (year of birth), which is more stable. Alternatively, more information in the dataset's metadata.