A condition for time series when the basic (long-term) trend and the recent (short-term) trend are forecasted to be in opposite directions. When it occurs, trend extrapolation is risky. One strategy is to blend the two trends as one moves from the short to the long term. A more conservative strategy is to forecast no trend. For evidence on how inconsistent trends affect forecast errors, see Armstrong, Adya and Collopy (2001). See also consistent trends.

Armstrong, J. S., M. Adya & F. Collopy (2001), “Rule-based forecasting: Using judgment in time-series extrapolation,” in J. S. Armstrong (ed.), Principles of Forecasting. Norwell, MA: Kluwer Academic Press.