Buyer/Seller Ratio - Relevant?

[Thierry Van Roy]

A French Zillow-ish site (MeilleursAgents.com) has mapped out the buyer/seller ratio for its markets. They consider it a more reliable indicator of where the market is going than anything else.

Their rule of thumb:

more than 3 buyers for every seller: appreciating market

2-3 buyers for every seller: stable market

less than 2 buyers for every seller: depreciating market

The fluctuations are impressive: Paris went from 6 to 1,4 buyers for every seller in a few years. Because of this, they expect the prices to drop double the official estimates.

Now I wonder, is this a reliable indicator? Does anyone have experience with this, because google only talks of this indicator for stock options.