29.23. Data can typically be presented in raw, seasonally adjusted, calendar-adjusted only or trend-cycle form. The raw data contain all the characteristics of the time series. As the seasonally adjusted data contain the trend-cycle and the irregular components, they contain the “news” of the series. Much of the discussion on trend-cycle analysis focuses on the so-called end-point problem. Since the trend-cycle values at the end of the series are usually estimated by extrapolation, the estimated trend-cycle for the most recent data is very uncertain and can suffer from phase-shift[15] problems. Particular care is required at turning points, where it often takes months until the new correct direction of development appears. In addition, it is good practice to monitor discrepancies between the trend of raw data and the trend of seasonally adjusted data.
29.24. In all cases, the information contained within the press release should reflect the principles of ensuring transparency and assisting users in making informed decisions.
[15] A phase shift is the amount of horizontal change of a wave pattern from its original state.