What are time series?
Time series are any data series where the same measurement is taken at a number of equally spaced periods of time. They are used to trace the pattern of the observed variables.
What is seasonal adjustment?
Seasonal adjustment is a process by which changes that are due to seasonal or calendar influences are removed to produce a clearer picture of the underlying behaviour.
Aims
Time series analysis provides a source of expertise on the time series methods that are used to produce ONS and Government Statistical Service (GSS) statistics. This includes providing advice and quality assurance on methods for seasonal adjustment, trend estimation, and forecasting.
Seasonal Adjustment provides annual reviews of the seasonal adjustment undertaken by each business area in ONS. These reviews evaluate the seasonal adjustment processes currently used, assess how well these processes have worked since the previous review and advise on how they should be altered to ensure the best performance in the future.
The team also provides training and guidance to business areas in ONS and the GSS on seasonal adjustment using X11ARIMA, which is a software package incorporating ONS's chosen methodology.
Current and planned areas of work
Recent work has included the development of an improved suite of methods and tools for time series analysis as part of the ONS modernisation programme. This will include moving from X11ARIMA to a later version, X12ARIMA, as the standard method of seasonal adjustment. In order to ensure a smooth transition to the modernised system the programme will develop training material including a Guide to Seasonal Adjustment with X12ARIMA and courses on the new methods and tools.
This page last revised: Thursday 11 March 2004
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