Stock Market Data Normalization For Time Series

Stock Market Data Normalization For Time Series

In the world of stock market analysis, understanding and comparing the movements of different stocks over time is crucial for making informed investment decisions. This article introduces 10 powerful normalization techniques for stock price time series data that can help you gain valuable insights, compare stock performances more effectively, and prepare data for machine learning applications. By mastering these methods with itAdviser, you’ll be better equipped to navigate complex financial markets and make more strategic trading choices.

Z-score normalization (Standardization)

Z-score normalization, also known as standardization, is a commonly used technique for normalizing stock price data. It scales the data to have a mean of 0 and a standard deviation of 1.


Z = (X - μ) / σ


  • Z is the Z-score (normalized value)
  • X is the original stock price
  • μ is the mean of the stock price for the given time period
  • σ is the standard deviation of the stock price for the given time period

Min-Max Scaling (Normalization)

Min-Max scaling is another popular technique for normalizing stock price data. It scales the data to a specific range, typically [0, 1].


X_normalized = (X - X_min) / (X_max - X_min)


  • X_normalized is the normalized value
  • X is the original stock price
  • X_min is the minimum stock price for the given time period
  • X_max is the maximum stock price for the given time period

Percentage Change

Percentage change is a simple and effective method to analyze the relative movement of stock prices in a time series. It measures the change in price as a percentage of the previous period’s price.


Percentage Change = ((Current Price - Previous Price) / Previous Price) * 100

This method is particularly useful for comparing the price movements of different stocks, as it puts the changes in stock prices on a relative scale, independent of the stock’s actual price level.

Log Returns

Log returns are another popular method used to normalize stock price movements in a time series. This method is commonly used in finance, as it has several desirable properties, such as being additive over time and having a more symmetrical distribution.


Log Return = ln(Current Price / Previous Price)

Where ln is the natural logarithm.

Moving Average Normalization

Moving average normalization smoothens out the price data by calculating the moving average of the stock prices over a specified window (e.g., 5 days, 20 days, 50 days, etc.). The normalized value is calculated by dividing the stock price by its moving average.


Normalized Value = Current Price / Moving Average

Choose the normalization technique that best suits your needs and the specific requirements of your analysis. For instance, if you need to compare the relative performance of different stocks, percentage change or log returns might be more appropriate. On the other hand, if you need to apply machine learning algorithms, z-score normalization or min-max scaling might be more suitable, as these techniques transform the data into a more standardized format.

Detrended Price Oscillator (DPO)

The Detrended Price Oscillator (DPO) is a technical analysis tool that removes the trend from the stock price data, making it easier to identify and compare price cycles. DPO can help to normalize stock price movements by eliminating long-term trends, focusing on short-term fluctuations.


DPO = Price - Simple Moving Average(N/2 + 1 periods)

Where N is the chosen period for the oscillator (e.g., 20 days, 50 days, etc.).

Cumulative Return

Cumulative return is a useful metric for comparing the overall performance of different stocks over a specified time period. It measures the total percentage gain or loss from the beginning of the time series to each subsequent point in time.


Cumulative Return = (Current Price / Initial Price) - 1

This method helps to normalize stock price movements by presenting the returns in terms of percentage gain or loss, making it easier to compare the performance of different stocks regardless of their initial price levels.

Normalized Average True Range (NATR)

Normalized Average True Range (NATR) is a technical analysis indicator that measures the stock price’s volatility, normalizing the price data by the stock’s average true range.


NATR = (Average True Range / Current Price) * 100

This indicator can help to normalize stock price movements by accounting for their volatility, making it easier to compare the price movements of different stocks with varying levels of volatility.

Relative Strength Index (RSI)

The Relative Strength Index (RSI) is a momentum oscillator that measures the speed and change of price movements, normalizing the data to a range of 0 to 100. RSI is useful for identifying overbought or oversold conditions and can be used as a basis for comparing the price movements of different stocks.


RSI = 100 - (100 / (1 + RS))


  • RS is the average gain of up periods divided by the average loss of down periods over a specified time frame (e.g., 14 days).

Sector-Based Normalization

Another approach to normalize stock price movements is to compare the performance of individual stocks with the performance of their respective sectors. This approach involves calculating the percentage change for each stock relative to the sector’s average performance over the same time period.


Normalized Sector Performance = (Individual Stock Performance - Sector Average Performance) / Sector Average Performance

This method helps to put the stock price movements into context by comparing them with the overall performance of their respective sectors, making it easier to identify the outperformers and underperformers within each sector.

In conclusion, the choice of normalization technique depends on the specific goals and requirements of your analysis. Some methods are more suitable for comparing stocks’ relative performance, while others are better for preparing data for machine learning algorithms. It’s crucial to understand the underlying assumptions and characteristics of each technique to ensure that the chosen method aligns with your analytical objectives. Also, consider combining multiple techniques or using them in conjunction with other technical analysis indicators to gain a more comprehensive understanding of stock price movements and market dynamics.

When working with stock market data, it’s essential to remain aware of the limitations and potential biases of each normalization technique. Additionally, always consider the influence of external factors such as market conditions, macroeconomic factors, and company-specific news on stock prices. Incorporating these aspects into your analysis will provide a more robust and accurate representation of stock price movements and support better decision-making in the context of investing and trading.

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