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.