Seasonality in the San Diego economy
Tóm tắt
The Union-Tribune Index, a basic source of economic data for San Diego County, is seasonally adjusted using the X-11 Variant of the Census Method II Seasonal Adjustment Program. In this study, the resulting description of seasonal patterns was evaluated using additional statistical techniques. Specifically, the X-11 Program's Test for Stable Seasonality (an analysis of variance) was extended through use of the Newman-Keuls Multiple Range Test. Also, a check was made to see if one of the necessary assumptions of the Test for Stable Seasonality was satisfied. The results indicated that the X-11 does an inadequate job for many San Diego County time series. Its implicit seasonal patterns do not coincide with those indicated by the range test. Further, the X-11 will “seasonally adjust” data even when its own test for stable seasonality indicates no seasonal behavior or when the test results are ambiguous due to a necessary assumption not being fulfilled. While not a seasonal adjustment procedure, the Newman-Keuls Multiple Range Test is a better way to describe seasonal patterns.
Tài liệu tham khảo
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