Australian Bureau of Statistics
1346.0.55.003 - Interpreting Time Series: Are you being misled by the Seasons, 2012
Latest ISSUE Released at 11:30 AM (CANBERRA TIME) 11/12/2012 First Issue
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REVISIONS TO TIME SERIES ESTIMATES
Figure 4: Short term visitor arrivals to Australia from Japan, Seasonally Adjusted Estimates
Figure 4 shows seasonally adjusted estimates for June, July and August 1990. The different estimates produced in different years shows how the seasonally adjusted estimates change as additional information becomes available.
Revisions are improvements to the seasonally adjusted estimates as seasonal patterns in the original estimates become clearer over time.
WHEN WILL TREND ESTIMATES BE REVISED?
Trend estimates also face minor levels of revision as more data becomes available. This occurs as both the seasonal pattern and the underlying direction of the series become clearer. Usually the largest revisions occur in the three time periods following the initial trend estimate. For example September 2005 trend estimates will normally face revision in October 2005 and be relatively stable after December 2005.
Figure 5: Short term visitor arrivals to Australia from Japan, Trend Estimates
Figure 5 shows that trend estimates for September 1990 are revised as more original estimates become available. The size of these revisions becomes smaller over time. We have selected an unusually drastic example for clarity.
Revisions are improvements to the trend estimates as seasonal patterns and the underlying level of the original estimates become clearer over time.
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This page last updated 10 December 2012