Cannot determine the opening direction.

Generally speaking, Bollinger's closing only indicates that the market may change. As for which direction it will change, it is not certain.

In a few cases, it can even continue to fluctuate within a narrow range for a long time.

Standard investment evaluation usually pursues a certain margin of safety. The upper and lower Bollinger tracks can be regarded as this safety margin, or known as the credible interval.

However, due to the complexity of human social psychology (metabolism, profitability, adaptability, plasticity, stress, variability and rhythm), this margin is often only theoretical or idealized , for reference only.

The calculation of Bollinger Track introduces the concept of statistical standard deviation.

Calculation formula of daily BOLL indicator:

Middle track = N-day moving average

Upper track = middle track + twice Standard deviation

Lower track = middle track - twice the standard deviation

It can be seen that the distance between the upper and lower Bollinger tracks gradually shrinks - that is, the closing, indicating the standard deviation. Gradually narrow, that is, the fluctuations tend to narrow.

In terms of stock price performance, it has entered a period of calm.

Also due to the complexity of social psychology, this calm period cannot be maintained forever, and changes will inevitably occur.

When the stock price breaks through the narrow upper rail or lower rail, the standard deviation of the stock price will gradually increase, that is, the volatility will increase. At the same time, it also means the expansion of the "margin of safety" and the return of violent fluctuations to normal.

A long-term narrow range fluctuation is unlikely to appear at the top. It may appear at any position: at the bottom, rising relay or falling relay.