My interpretation of Walid Khalil's Volume Zone Oscillator (VZO) as published in the 2009 International Federation of Technical Analysis Journal.
This VZO indicator is also the same as Danielle Shay's popular Simpler Trading TurboVZO indicator.
ABOUT: The oscillator breaks up volume activity into positive and negative categories. It is positive when the current closing price is greater than the prior closing price and negative when it's lower than the prior closing price. The resulting curve plots through relative percentage levels that yield a series of buy and sell signals, depending on level and indicator direction.
HOW TO USE THE INDICATOR: The default period is 14 but can be adjusted after backtesting.
The VZO points to a positive trend when it rises above and maintains the 5% level, and a negative trend when it falls below the 5% level and fails to turn higher. Oscillations between the 5% and 40% levels mark a bullish trend zone, while oscillations between -40% and 5% mark a bearish trend zone. Meanwhile, readings above 40% signal an overbought condition, while readings above 60% signal an extremely overbought condition. Alternatively, readings below -40% indicate an oversold condition, which becomes extremely oversold below -60%.
Kahlil recommends confirming VZO signals with a 14-period average directional index (ADX), with values greater than 18 pointing to a trending market - search Tradingview's built-in indicators for the Directional Movement Index (DMI).
INTRADAY SCALPING: Whilst the VZO is already smoothed with an exponential moving average, the indicator settings include an additional 'smoothing' function to remove any excess 'noise' in the plots for intraday use.