The X-11 seasonal adjustment program can be viewed as being
based on linear filters composed of seasonal, nonseasonal, and
Henderson trend moving averages. This view is exact for the
additive decomposition (apart from modifications to deal with
extreme values), and approximate for the multiplicative
decomposition (Young 1968). Adopting this view, we consider all the
X-11 symmetric linear filters for estimating the seasonal,
nonseasonal (seasonally adjusted), trend, and irregular components,
that are available from all the possible choices of X-11 filter
options (seasonal and Henderson trend moving averages). This report
presents graphs of the filter weights and filter squared gains for
all these symmetric linear filters.
C. Monsell is Mathematical Statistican, Statistical Research
Division, U. S. Census Bureau, U.S. Census Bureau,
4600 Silver Hill Road, Washington, DC 20233. email :
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