Definition: Calendar

National accounts

The timing of certain public holidays, such as Christmas and Easter, clearly effect some series, particularly those related to production. Many series are recorded over calendar months, and as the number of working days varies considerably from one month to another, in a predetermined way, this will cause a seasonal movement in flow variables, such as imports or production. The working days problem could also lead to spurious correlation between otherwise unrelated series.
Handbook on quarterly national accounts, 1999 Edition, Eurostat, p.200

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