Correlation Coefficient Indicator Formula and Example

Statistically speaking, we say two sets of data or two variables as correlated if there exists a statistical relationship (linear interdependence) between them. If two data sets or variables have a strong statistical relationship between them, we identify them as highly correlated. Correlation Coefficient summarizes these two data sets into a single number betweel +1 and -1.

Correlation Coefficient FAQ

How do you calculate a correlation coefficient?

This is a popular method of summarizing a set of numbers into one single number between -1 and +1. Say we will find relation benween four movies. If we represent graphically, say we plotted the length of the movied in the X axis. And in the Y axis we have plotted their ratings. Now, we will fit a straight line to the data. Now we will check if the straight line is pointing upwards or downwards. So is it positive or negative. In our example we saw that the straight line is positive, so the correlation coefficient is also positive. It is between 0 and +1.Positive Correlation Coefficient
Similarly if we find the line is sloping downwards it is a negative relation. Check the image below. Here the line is sloping downwards indicating a negative correlation. The correlation coefficient is between 0 and -1 here.Negative Correlation Coefficient
In case we get a horizontan line without any significant slope we tell it as a neutral correlation.

What is coefficient correlation?

This is actually a method of summarizing a set of number or data sets into an one single number between +1 and +1. We can find the mutual relation of any data sets like movies, cars, cities anything and find how they are mutually related. We can use this method in the stock market too, to find the correlation between two or more stocks.

What is a strong correlation coefficient?

Correlation coefficient can be between -1 to +1. The more it is close to +1 the more correlated or stronly correlated the datas are.

What is Correlation Coefficient indicator and how it is used in the stock market?

Investopedia defines this indicator as a measure the degree of correlation between two stocks. The value of the coefficient varies from -1 to +1. For pairs trading, we should choose a pair of different stocks with positive correlation. That means value of correlation coefficient indicator will be between 0.00 to 1.00. The closer it is to 1, the better. We use this coefficient in pairs trading strategy.

How to set up Correlation coefficient Indicator on your chart?

  • SIf you are using Zerodha Kite, follow the below mentioned steps.
  • Select the stock you will trade from your MarketWatch .
  • Open the chart of that stock.
  • From the Studies section go to Correlation Coefficient and click on it.
  • The default parameter window will open showing 14 as the default period.
  • Click the DONE button and the indicator will plot on the charts.
  • But you can only see a blank window on the chart because this indicator will only be activated if you compare one stock with another.
Correlation Coefficient Indicator

Usage of Correlation coefficient Indicator

For health check up of diversified portfolio by comparing stocks side by side

Time needed: 1 minute.

How to compare stocks side by side in Zerodha?

  1. Click the 3 vertical dots

    The picture below shows the correlation between SBIN (State Bank of India) and ICICI Bank. To compare two stocks open the chart of one stock (here State Bank of India) and click the three vertical dots beside the name. This will bring up the Compare option.Compare Stocks Zerodha

  2. Select the stock you want to compare

    Now click on the Compare option. This will open up a drop down list. Select the stock you want to compare from this drop down list. Here we selected ICICI Bank.Compare Stocks Zerodha

  3. Add 2 stocks side by side

    This will add the two stocks side by side. If you have the Correlation Coefficient indicator attached to the chart you can see now the indicator is visible and ready to correlate these two stocks.Correlation Coefficient Indicator Zerodha

Correlating two stocks

As we know the Correlation Coefficient indicator can compare two stocks side by side. Here if SBIN and ICICI Bank moves in same direction with same magnitude, the indicator will also start moving in that direction. This indicator is an oscillator and it oscillates between +1 to -1. When the indicator is close to +1 it means these stocks are perfectly correlated. If SBIN rises by 5%, ICICI Bank will also tend to rise by almost 5%. And when the indicator is in negative territory, it indicates the stocks are not well correlated. We can find the winner or laggard in our portfolio in this way by correlating them.

The Correlation Coefficient indicator can also be used to determine the correlation between a stock and an index or a stock with an exchange-traded fund (ETF). This indicator is positive when both securities move in the same direction, either up or down and it’s negative when both securities move in an opposite direction. A reading above 0.5 denotes a strong correlation while any reading below -0.5 denotes a very wide divergence.

Tweaking the default parameter

To monitor the correlation over a long period of time, we may change the default settings of the indicator. Let us make it 100 from 14. This will make the indicator smooth and can find the correlation between two stocks over a long period of time. Watch the image below.

Correlation Coefficient Indicator

Pair Trading using Correlation Coefficient indicator

We can do pair trading in two stocks using this compare option and correlation coefficient indicator. Create a short sell in SBIN and a long position in ICICI Bank when the correlation is above 0.5 and closer to 1. Make the trades simultaneously. Exit when the price reverses and correlation goes below zero. Both the exits have to be done simultaneously. Pairs trading strategy follow mean reversion theory.

The indicator works well in daily time frame creating buying and selling opportunities simultaneously. For pairs trading, other indicators are also used in conjunction this indicator.

Conclusion

The correlation coefficient indicator correlates two stocks or indices. It is now available in major Indian trading platforms like Zerodha Kite etc. The indicator oscillates between a reading of +1 to -1. A reading close to +1 means the stocks are closely correlated and a reading close to -1 denotes the stocks are not so well correlated. This indicator can also be used for pair trading.

Author: Indrajit Mukherjee

Indrajit is a professional blogger and trading system developer. Amibroker expert, Wordpress expert, SEO expert and stock market analyst.Trading since 2002, he has started the journey of StockManiacs.net on 2008. He follows Indian and world stock markets closely.

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