The STD function in ProBuilder language calculates the standard deviation of a given price series over a specified number of periods. Standard deviation is a statistical measure that quantifies the amount of variation or dispersion of a set of values. In financial markets, it is commonly used to assess the volatility of an asset’s price.

Syntax:

STD[N](price)

This function takes two parameters:

• N: The number of periods over which the standard deviation is calculated.
• price: The price series (e.g., close, open, high, low) from which the standard deviation is to be calculated.

Calculation:

The standard deviation is calculated using the following formula:

STD = SQUAREROOT[(summation(from d = 1 to N) (price - MovingAverage[N](price))^2) / N]

Here, MovingAverage[N](price) represents the simple moving average of the price over N periods.

Example:

mySeries = close
statisticalDeviation = STD[10](mySeries)
RETURN statisticalDeviation

In this example, the standard deviation of the closing prices over the last 10 periods is calculated and returned.

Interpretation:

The standard deviation is a key measure of volatility. A higher standard deviation indicates higher price volatility, while a lower standard deviation indicates lower price volatility. It is often used in conjunction with other indicators, such as Bollinger Bands, which typically plot lines two standard deviations above and below a moving average.

Understanding the standard deviation can help traders gauge the risk and volatility associated with an asset’s price movements, which is crucial for making informed trading decisions.