Better Bollinger Bands "

Better Bollinger Bands "
In a future article in a magazine, October 1998, Dennis McNicholl describes the use of Bollinger Bands and provides a means of making them tighter when markets are trending. He calls them Better Bollinger bands.

Here is the formula for MetaStock 6,5 or higher.

PDS: = Input ("periods", 2,200,20);
sd: = Input ("standard deviation" .01,10,2);
Alpha: = 2 / (PDS +1);
t: = alpha * C + (1-alpha) * (If (Cum (1) + PDS, C, previous));
Ut: = alpha * t + (1-alpha) * (If (Cum (1) + PDS, C, previous));
DT: = ((2-alpha) * mt-ut) / (1-alpha);
mt2: = alpha * ABS (C-dt) + (1-alpha) * previous;
ut2: = alpha * mt2 + (1-alpha) * previous;
dt2: = ((2-alpha) * mt2-ut2) / (1-alpha);
but: = dt + SD * dt2;
BLT: dt =- SD * dt2;
DT;
but;