2014issue C0255

Industry-group quartile pivots as a Bollinger Bands case study

This case study teaches Bollinger Bands as a lookback envelope on ordered, normalized industry-group prices. Quartile ranks are specified first. Later overbought or oversold pivots are then read as an out-of-sample check on that envelope.

Compare industry groups only after restating each series as a normalized group price, kept as daily open, high, low, and close observations.
Specify a lookback and turn momentum ratios into quartile ranks before treating any later extreme as informative.
A power shift is a change in group strength after an overbought or oversold condition; a pivot is the later reversion point.
Editorial reading: use those later pivots as an out-of-sample check on the envelope, not as a live trading cue.

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Current trackBollinger Bands84 readings

A group-level forecast envelope

Industry groups can be compared after prices are restated as a normalized group price within each group. Each group is carried as daily open, high, low, and close observations. A normalized group price restates those series onto a common scale so ranks and envelopes can be compared across industries.

Editorial interpretation: Bollinger Bands are taught here as a lookback envelope around a central tendency of those ordered prices. The envelope frames industry-group extremes as a forecast-style baseline. Students specify the sampling interval and lookback first, place the series into quartile ranks, and only then inspect later overbought or oversold pivots.

Momentum ratios and quartile ranks

Momentum can be specified as a momentum ratio, which is the current price divided by a prior price over the chosen sampling interval. Those ratios can be ranked or assigned to quartiles. A quartile rank is the peer placement of a group after that comparison, in one of four ordered buckets.

The same view can change the observation date, the chosen quartile, and whether the rank is short-term, intermediate-term, or long-term. A short-term rank is computed on the shortest of the available lookbacks and can sit beside the longer-horizon ranks. Short-term momentum can also be shown as a separate plotted series on the quartile-mover chart.

Quartile-mover, momentum-mover, and pivot displays

A quartile-mover view can list leading industry groups in several sortable categories. That view can be switched among quartile-mover, momentum-mover, and power-shift-and-pivot displays.

New first-quartile groups by daily price change

Among industry groups that had just entered the first quartile, Coal is the only double-digit gainer at 12 percent, while the other eleven names cluster between 2.33 and 4.49 percent. The figures are the price-change column of the Group Power quartile-mover table for 10 October 2013, short-term rank.US industry groups · Daily snapshot, 10 October 2013 · 2013-10-10T00:00:00.000Z to 2013-10-10T00:00:00.000Z

The source listed groups newly in the first quartile and sorted them by short-term rank change, not by price change. Gas Producers ranks fifth on that sort but second on price change.

Power shifts and later pivots

Power-shift and pivot logic treats an industry group as able to become overbought or oversold. The group may then strengthen after an oversold state or weaken after an overbought state. A power shift is that change in group strength, seen as movement in the opposite direction.

After an overbought or oversold move, group prices may revert. Those reversion points are labeled pivots. An out-of-sample check applies the historically specified ranking or envelope rule to later observations to see whether the baseline still describes the path.

Editorial interpretation: the later pivot is the check on the envelope. It is not a live trading cue.

Daily summary and on-screen help

A daily summary can cover six weeks of history. It can compile group trends, new highs and lows, short-term momentum rankings, and strongest and weakest money-flow groups. Screen headers can include context-sensitive help that opens an explanation of the selected item, alongside a support section written like a user manual.

Educational research material, not investment advice. Historical source context does not establish present-day performance.

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201457-58 pp.Next on Bollinger BandsBollinger Bands as adaptive price envelopes: a 2014 classroom caseBollinger Bands were introduced in the 1980s as fully adaptive trading bands, meaning volatility-scaled envelopes around a moving central price line rather than a constant offset.

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