Evaluating double bottoms with a locked stochastic confirmation

A two-layer falsification drill

A double-bottom is a two-trough price structure whose intervening peak and later breakout define a testable reversal hypothesis rather than a finished forecast. A stochastic-oscillator is a bounded reading of where the latest close sits inside a chosen lookback range, computed on daily or weekly bars. Overbought-oversold is an extreme oscillator print that marks location inside that lookback range and does not, by itself, assign trade direction.

Editorial interpretation: run those definitions as two stacked checks. First ask which geometric traits of a double-bottom still sort a historical sample after crude filters are stripped away. Then lock each stochastic-oscillator reading to an independent-confirmation rule so the same overbought-oversold print cannot silently change meaning.

What still sorted the sample

A 2018 reader evaluation assembled 3388 manually identified double bottoms from 1080 stocks covering 1991 through 2018. Pattern-height, the distance from the trough structure to the breakout price, remained the attribute used to order short, middle, and tall groups. That evaluation used the median height-to-breakout price as the cutoff between short and tall double bottoms.

Bottom-to-bottom price variation and volume were treated as non-discriminating attributes in that sample. The same three height bands, 0-10 percent, 10-20 percent, and more than 20 percent, were kept as the comparison frame once other screens were removed.

Filters that were stripped away

A 100000-share floor on breakout-day-volume was omitted because it cut the usable sample from more than 2000 cases to 164. Breakout-day-volume is share turnover on the session that clears the intervening peak. A hard share-count floor can shrink the usable sample sharply.

Screens that dropped stocks priced under 5 or over 500 were also omitted so those three height bands could be compared without those price limits.

Rules that were retained

Two retained rule checks were a left bottom priced above the right bottom, and right-bottom volume, averaged over the five sessions from two days before through two days after the trough, exceeding left-bottom volume. That comparison uses a bottom-volume-window: a short symmetric window around each trough, such as two sessions before through two sessions after, used to compare activity at the right bottom with activity at the left.

When one oscillator print means two things

A contemporaneous letter observed that an oversold daily stochastic-oscillator during an uptrend was described both as a potential long-side setup and, on one illustrated advance, as a reading that preceded a decline. The same letter cited a weekly stochastic-oscillator that was overbought at the start of April and already trending lower, after which no upside reversal appeared.

The author's reply treated identical oscillator or pattern signals as messages that can differ by context and described a signal as a possibility rather than a guaranteed outcome. The reply specified a 200-day simple moving average plus support and resistance as extra confirmation and stated that weekly and daily stochastics should be read together with those tools. Independent-confirmation is a second, separately defined condition such as a long moving-average location or a support and resistance test that can ratify or reject the first signal.