Dylan’s BI Study Notes

My notes about Business Intelligence, Data Warehousing, OLAP, and Master Data Management

13 Period Calendar

Posted by Dylan Wan on February 26, 2008

I will discuss the following topics:

  • What is the 13 period calendar?
  • Who uses the 13 period calendar?
  • How is it different from the 4-4-5 calendar?

A 13 period calendar is different from a 4-4-5, 4-5-4, or 5-4-4 calendar. A typical Gregorian calendar month has 12 months and the number of days in a month vary depending on the month. In a 13 period calendar, a year has 13 period and each period has 4 weeks. In a 13 period calendar, you do not have the quarter or half year concept. Each year has 13 periods, each period has 4 weeks, and each week has 7 days.

Each period in a 13 period calendar may still be called “month”, but the month has only 28 days. You can still see the mertic like “last month sales”. You can also report by week and does a weekly summary. You can also have a 13 rolling periods.

A 13 period calendar is commonly seen as a sales calendar. The major drawback is that a 13 period does not have “quarter”, which is a required reporting period for financial reporting (10-Q). I guess that the 13 period calendar must hardly be the “fiscal” calendar.

The difference between 13 period calendar and a 4-4-5 calendar is that the number of days in each period is equal in a 13 period calendar and thus you can do a period to period basis comparison and trending under the 13 period calendar. Both the 13 period calendar and the 4-4-5 calendar allow you to compare a period to the same period from a prior year. Both the 13 period calendar and the 4-4-5 calendar support “week”. This is the major benefit comparing to the Gregorian calendar.

In a 4-4-5 calendar, each year has 12 month period, but the number of days in each period is not equal. You can do a week by week and quarter by quarter analysis, but period by period is only meaningful when comparing the data with the same period from a prior year, not comparing with the last period of this year. A 4-4-5 calendar is actually a 13 week quarter calendar.
The calendar hierarchy is like below:

4-4-5 Calendar:

Year -> Half Year -> Quarter-> Period -> Week -> Date

13 Period Calendar:

Year -> Period -> Week -> Date

See Also: The 4-4-5 calendar.

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5 Responses to “13 Period Calendar”

  1. TheAbysmal said

    you are perpetuating a common misconception.

    a 13-period calendar divides the year into 52 weeks (+1 day +1 leap year day).

    The year divides evenly into 4 quarters of 13 weeks, or 13 months of 4 weeks, or 2 halves of 26 weeks.

    If you measure your year in 52 weeks, then it becomes a more eloquent means of counting the days. Can you imagine if bi-weekly and monthly events (like bills & rent & paycheques) all synchronised with one another? It would make accounting so easy that we would require far fewer hours working on our budgets.

    simple, no?

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