What is the calculation for the positive directional movement (+DM)?

The calculation for positive directional movement (+DM) is derived specifically to gauge the strength of upward price movement in a security. It is calculated by taking the current day's high and subtracting the previous day's high. This gives a measure of how much the price has increased compared to the last period, allowing traders to understand the momentum of price movements.

In the context of the choices provided, option B accurately reflects this calculation. If the current day's high is greater than the previous day's high, the result will show a positive directional movement. If the current day's high is less than or equal to the previous day's high, then +DM is zero, since there is no upward movement to account for.

Understanding this calculation is crucial for anyone studying technical analysis, especially when using indicators like the Average Directional Index (ADX) to assess market trends and strength. This focus on the relationship of highs in consecutive periods helps traders identify bullish trends effectively.