Imbalances and how they stack

An imbalance is a price where one side crushed the other diagonally. The most common rule: there is a buy imbalance when the volume at the ask of a price is at least three times the volume at the bid of the price just below; a sell imbalance when the volume at the bid of a price is at least three times the volume at the ask of the price just above. The threshold is adjustable (200%, 300%, 400%), but 300% is a good starting point.

An isolated imbalance happens all the time and says little. What interests the order flow reader are stacked imbalances and the ones that appear in the wrong place.