The Disparity Index is a technical indicator that measures the relationship between the current price of an asset over its moving average. Its development is attributed to Steve Nison based on his book Beyond Candlestick.
The Disparity Index can take positive and negative values. A positive value indicates that the asset price is increasing rapidly, while negative values indicate that the price is falling. A value of zero indicates that the current price of the asset moves in line with the moving average.
When the Disparity Index crosses the zero level that reflects a rapid change in price direction and thus it can be taking an early indicator of increased momentum (force) in the direction indicated.