Deviation systems are also known under the French name: “Ecarts”.
The theory runs like this: on even money bets over a long period of time you would expect to see 50% red and 50% black (we are ignoring the zero pocket for the moment for the purpose of illustration). In practice, you are likely to see a deviation, certainly after 100 bets and probably after a 1000 bets. You’ll see 93 reds and 107 blacks for example. It is highly unlikely that you would see 500 odds and 500 evens after 1000 spins (although you might).
Many people try and use this deviation or “Ecart” to gain an edge over the casino. The deviation can be as much as 10%, even in quite long sessions at the table.
Several roulette systems try and use this as their “gold dust”. You measure the deviation and if it hits a certain point in the favour of one colour (or other even chance bet type), you weight your bets accordingly.
Ther are a number of these types of triggered betting systems, that are also know as “Marches”. The classic ones are as follows:
- The Alternate, or Sauteus- you predict a regular alternating even money bet, e.g. odd, even, odd, even.
- You bet on the last colour that came in (The Gagnate)
- You bet against the last colour that came in (The Perdante)
- You wait for a colour to hit twice and bet on that colour.
- You wait for a colour to hit twice and bet against that colour.
- The Avant-derniere: you bet on the penultimate winning colour- ie the result before the last one.
One thing you may notice about these systems, is that they generally have an opposite version- ie a system that runs in exactly the opposite fashion.
You may ask yourself: “Hang on a minute. If the first system works, why would there be a system that says to do exactly the opposite”.
Errrr, that would be a good question Sherlock. Merde. And, ummmm. Anyway- don’t worry your pretty little head about that. Allez!