I have placed two red boxes and two green boxes on the chart. The larger red box depicts all of the historical movement, from a percentage standpoint, that this stock has moved on the after a SELL signal occurred. Therefore, this box represents 100% of previous movement upward before the stock finally moved downward. The smaller red box represents 50% of all historical movement upward, before the stock moved downward. The smaller box is more of a precise target for the potential top in this instance.
The green boxes represent the same thing. In this instance, the smaller green box would be my projected target for the final bottom.
The black dotted arrow represents median historical movement. Medians are a good metric, but they are just one of many I use when forecasting future movement.
As always, the stock could decline the very next bar after the signal without looking back (therefore the red boxes would not come into play) or the stock may never decline (and the green boxes may never come into play).
All statistics and the full analysis are available for free as always at the site below.