Money Management & Positive Expectancy

A good trading system gives you an edge in the market.
To use a technical term, it provides a positive expectancy over a long series of trials.
A good system ensures that winning is more likely than losing over a long series of trades.
If your system can do that, you need money management.
But if you have no positive expectancy, no amount of money management will save you from losing.

Dr Alexander Elder, Come Into My Trading Room