One of the commonly used technical indicators, reading boll Bollinger line indicators

What is Bollinger line index ？

The brin line BOLL indicators (Bollinger Bands) It is one of the commonly used tools for technical analysis of the stock market , By American financial analysts John Bollinger According to the moving average and the principle of standard deviation in Statistics 1980 Designed in the s .

As shown in the figure above , Bollinger line indicators from the top 、 in 、 The next three tracks form , Among them, the upper, middle and lower tracks can be regarded as the pressure line of stock price 、 Average line and support line , The stock price fluctuates within the range of upper limit and lower limit, that is, the stock price channel . The stock price channel will change with the fluctuation range of the stock price . The Bollinger line generally takes 20 Day as a parameter .

Brin line formula description

Middle track = N Daily moving average ,N Usually take 20

Upper rail line = Middle track + X Times the standard deviation ,X Usually take 2

Lower track = Middle track －Y Times the standard deviation , Y Usually take 2

Bollinger line index calculation

1. talib Brin line index is used in

import talib
 
upper, middle, lower = talib.BBANDS(close, timeperiod=20, nbdevup=2, nbdevdn=2, matype=0)

• Return value ：upper Is the upper rail line ,middle It is the middle track ,lower For the next track

• talib.BBANDS Function parameter ：close For the closing price ,timeperiod Is the calculation period , Usually take 20;nbdevup： The price of the upper track is a multiple of the standard deviation of the middle track , Usually take 2, The larger the value , The higher the upper limit , The wider the channel ;nbdevdn： The lower rail price is a multiple of the standard deviation of the middle rail , Usually take 2;matype： Moving average type ,0 Represents simple moving average

1. backtrader Brin line index is used in

import backtrader as bt

boll = bt.ind.BollingerBands(period=20, devfactor=2)

BollingerBands share 3 Parameters ,period Is the calculation period , Usually take 20;devfactor Is the multiple of standard deviation , Usually take 2;movav It is the moving average type , The default is simple moving average

Bollinger line index application

• The brin line can indicate the position of support and pressure , On 、 The middle track can exert pressure on the operation of stock prices , While in 、 Going down the track will support the operation of the stock market ; Brin line can show overbought 、 Oversold ： If the stock price rushes out of the upper track, it is possible to callback , The stock price may rebound after falling off the track

• The brin line can indicate the trend , Strong stocks are always in the middle 、 Between upper rail lines , The total operation of vulnerable stocks is below the medium rail line . When the price line is above the middle rail of brin line , It is mostly a long market , Can hold shares or buy ; And when the price line is below the brin line middle track , It is mostly a short market , Be careful when buying , The two poles of brin channel are upper rail and lower rail , It means extremely strong and extremely weak

• The narrowing of the upper and lower rails of brin hides a sudden change , Don't rush to buy . When the stock price K The amount of the line breaks through the upper track of the brin line , At the same time, when the originally narrow brin line channel suddenly opens upward , It shows that the stock price is about to enter a new rising channel , Should be based on buying ; Once the stock price K The line breaks through the lower track of brin line , At the same time, when the originally narrow brin line channel suddenly opens downward , It shows that the stock price is about to enter a new downward channel , It should be mainly sold

• When the stock price K When the line breaks through the middle rail line of brin line from below the middle rail line of brin line , It indicates that the stock price is relatively strong , Should be based on buying ; When the stock price K When the line breaks through the rail line of brin line from above the middle rail line of brin line , It indicates that the stock price is very strong , Share prices may rise sharply in the short term , It should focus on holding shares to be raised or short-term buying

• When the stock price K After the line has moved above the brin line for some time , If K When the line turns down and breaks through the upper rail of brin line , It indicates that the short-term strong market of stock price may end , Short term stocks should be sold in time , Especially those stocks with large short-term gains ; When the stock price K When the line breaks through the middle track of brin line , It should be mainly sold

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Reference resources

• https://en.wikipedia.org/wiki/Bollinger_Bands

• https://baike.baidu.com/item/ The brin line /3424486

• The Basics of Bollinger Bands

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