Scep, I also have the book. I bought it a few years ago from a second hand bookshop in Charing Cross road for £1.50. RWD claims that after years developing and researching the system he used it in 566 sessions, during which the numbers qualified a total of 1,202 times. Of those strings played, there were 413 winners and 789 losses, which gives a win rate of about 34.3%.

The probability of getting at least one hit for a single number in 9 spins is about 22%, so either RWD was lying or the sample size was too small. I don't believe he deliberately set out to deceive or that he wrote the book to make money; he was already a highly successful man at the time the book was written so why would he need to?

IMO he was just lucky with the system he created. He didn't understand statistical theory so didn't know how to draw the correct conclusion from his results, and so thought he had created a winning system. Indeed, he is quite scathing of mathematicians in the book, calling them "eggheads".

So things haven't changed much since the 1960's.

Out of curiosity I did test the system and needless to say the results were negative. The probability of a win in the 9 spins following the trigger came out at the expected 22%