By Ian Nunn ——Bio and Archives--January 11, 2014
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Seasonal adjustment is a statistical method for removing the seasonal component of a time series that is used when analyzing non-seasonal trends. It is normal to report seasonally adjusted data for unemployment rates to reveal the underlying trends in labor markets.
Fluctuations in economic time series are caused by seasonal, cyclical and irregular movements. A seasonally adjusted series is one from which seasonal movements have been eliminated. Seasonal movements are defined as those which are caused by regular annual events such as climate, holidays, vacation periods and cycles related to crops, production and retail sales associated with Christmas and Easter. It should be noted that the seasonally adjusted series contain irregular as well as longer-term cyclical fluctuations. The seasonal adjustment program is a complicated computer program which differentiates between these seasonal, cyclical and irregular movements in a series over a number of years and, on the basis of past movements, estimates appropriate seasonal factors for current data. On an annual basis, the historic series of seasonally adjusted data are revised in light of the most recent information on changes in seasonality.In short, seasonally adjusted numbers are real numbers with lipstick applied to make a pig more palatable to data analysis. They are made up numbers. Most honest data brokers will provide both seasonally adjusted and non-seasonally adjusted numbers. Statistics Canada is one such broker and the only real source of much economic data in Canada, particularly employment-related data. They have recently made their data available for free to the public through an online front-end to their data base. We look at two tables, CANSIM table2820087, Labour force survey estimates (LFS), by sex and age group, seasonally adjusted and unadjusted, and CANSIM 2820088, Labour force survey estimates (LFS), employment by North American Industry Classification System (NAICS), seasonally adjusted and unadjusted.
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Ian is a retired information technologist. While working at Health Canada he completed a BCS degree with highest honours at Carleton University in 1999. In 1998 he took a leave of absence from the federal government and worked as a consultant to Ontario Hydro Nuclear for 15 months in Y2K risk management. He retired from the government in 2000, went on to earn an MCS degree at Carleton, 2002, and subsequently completed the requirements for a PhD except for a dissertation.
Several years of graduate studies have equipped him to do thorough background research and analysis on topics he finds engaging. He is owner of the eclectic blog, The POOG. The acronym “POOG” came from a forgotten source: “pissed-off old guy”. A web search found a more flattering but accurate association: ”The mightiest of all men. He fights ignorant darkness in the name of wisdom, truth, courage, and honor.”
Ian lives in Ottawa.