a nice thing about the 2 per ROC is that its very simple to determine the # that will either maintain the current direction or turn it in the other direction
Day 1 = today's close
Day 2 = yesterday's close
Day 3 = close 2 days ago
then the # for tomorrow will be,
Pivot = Day 1 (-) Day3 (+) Day 2
coming into yesterday, the numbers for the Dow were,
Day 1 = 10123
Day 2 = 10065
Day 3 = 9993
Pivot = 10123 - 9993 + 10065 = 10195
the ROC had been up for 4 days, and to maintain the upward momentum it would take a close above 10195
since the Dow closed below that (10065), the ROC turned down
after watching it for a while, one can get the "feel" for when the market will really have to "reach" for the Pivot. and by knowing when the momentum is likely to turn, one can anticipate the movement, up or down, for the day
best to have 2 or 3 days in one direction before expecting the ROC to turn
there used to be some info about the 2 per ROC on the CME website, but can't seem to find it now, they're always changing things . . .