There is mention in William O'Neil's , How to Make Money in Stocks. He states that an impending up turn in the market occurs, after a decline of 10-12 percent, while the market continues to drop, the upside/downside volume starts to shift.
Zweig states a ratio of 9-to-1, with two signals in any 3-month perod, suggests a strong market to follow.
You can grab this shared layout in StockFinder, PatientFisherman_Upside_Downside_Vol.
* Ratio of positive numbers will always yield postive numbers.
Reference: Market Breadth Indicators, Gregory L. Morris