1995issue C071-6
Constructing regression projection bands and range oscillators
Separate least-squares slopes from a 14-bar window of highs and a 14-bar window of lows project every bar in the lookback. The rails are the extrema of those projections, and bandwidth plus a 0-100 oscillator are normalizations of that same pair.
- Separate least-squares slopes from a 14-bar window of highs and a 14-bar window of lows drive every later projection.
- The upper rail is the largest value among the current high and each earlier high advanced by its lag times the high-side slope; the lower rail is the smallest matching value on the lows.
- Projection bandwidth is 200 times the difference of the two rails divided by their sum, and the projection oscillator places the close on a 0-100 scale between those rails.
- The rails belong on the price scale, while the oscillator is drawn in a separate pane, with optional 20 and 80 guides and lookback left as an input.
Two slopes drive every projection
Separate least-squares slopes are taken from a 14-bar window of highs and a 14-bar window of lows, and those two slopes drive every later projection. Linear regression is used here only as that statistic: the least-squares slope of an ordered high or low series over a stated lookback. That slope is the only trend statistic needed to step each past extreme forward to the current bar.
A projection band is the current extreme among a family of highs or lows, each advanced by its bar lag times the matching regression slope. The upper rail is the largest value among the current high and each earlier high advanced by its lag times the high-side slope. The lower rail is the smallest value among the current low and each earlier low advanced by its lag times the low-side slope.
Bandwidth and oscillator restate the same pair
Projection bandwidth is the normalized width of the two rails, formed as 200 times their difference divided by their sum. The projection oscillator is the close expressed as a percentage of the gap between the lower and upper rails: it places the close on a 0-100 scale between those rails.
A slower companion series is an exponential smooth of that oscillator, using a 3-bar span in some recipes and a 4-bar span in another. Both series still point at the same two rails. Lookback is exposed as an input, with 14 as the suggested default, so the same construction can be rebuilt at other lengths.
Price pane and oscillator pane
The rails belong on the price scale because they are price projections, while the oscillator is a percentage and is drawn in a separate pane. Horizontal guides at 20 and 80 can be added so the oscillator is read with the same overbought and oversold framing used for a stochastic oscillator.
SOEX daily closes inside 14-bar projection bands

Separate 14-bar least-squares slopes on highs and lows. Mid-sample points are approximate digitizations, to the nearest index point. The 4 May rails were cross-checked against the printed close 493.54, bandwidth 2.35 and oscillator 53.50.
All readings on this track · 45 readings
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