GOING UP GOING DOWN - HOW GOOD ARE PEOPLE AT FORECASTING TRENDS AND CHANGES IN TRENDS

Prior studies of judgemental time-series forecasting have found that p eople have problems with downward-sloping series. This laboratory-base d study presents a controlled experiment of series direction and it in vestigates the problems of changing trends. Results confirm that peopl e have significant difficulties in dealing with downward-sloping serie s and that behaviour is consistent with a general tendency to anticipa te that downward series will reverse themselves. There is a significan tly less tendency to do so for upward series. Results are discussed in terms of systematic and unsystematic error. (C) 1997 by John Wiley & Sons, Lt d.