The Secular Trend is the long-term, non-periodic variation that occurs in a historical series versus periodic variation. Of course, if something is perceived as a secular variation or not depends on the times available: what seems to be a secular variation over a centuries-span can turn out to be a periodic variation over a million-year time span. Natural quantities often have periodic and secular variations.
The term secular trend is used everywhere you can apply historical series as in: economy, operational research, astronomy (celestial mechanics in particular), physical anthropology etc.
Jack McCormac said: "The angle of declination [the angle with which the astronomical north varies with the magnetic north] to a particular position is not constant but varies over time For about 150 years, there is a gradual passage inexplicable in the magnetic fields of the earth in a direction after which a progressive drift occurs in the opposite direction of completing the cycle over the next 150 years.This variation, called secular variation, can be very large. no known method for predicting secular change and all that can be done is to make observations of its dimensions around the world. Records, carried out in London for several centuries, show a series of magnetic declinations from 11th E in 1580 to 24 ° O in 1820. The time period between the extreme east and west declinations varies with the locality. It may be shorter than 50 years or even less and even 180 years or older more. "
For example, in the business operating cycle, revenue may change in the fiscal year. Experienced administrators may ignore cyclical revenue fluctuations and instead focus on the wider trend of year to year, hoping to see a centuries-old trend up. Notemodify wikitesto Bibliografiamodifica wikitesto Voices correlateemodify wikitesto
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