Quote from jessieblue:
How do you calculate expectancy? Should I make a note of all my trades and calculate in percentages my losses and wins than fill in the terms of that ecuation? or is it more like develloping an instinct.
No, jessieblue, you can't calculate an expectancy based on past performance of a trading strategy. This is because markets are statistically "nonstationary". The average behaviour of the market, or of any trading strategy, changes over time. The average behaviour you observe this week will be different from the behaviour you observe next week. The average behaviour you observe this year will be different from that you observe next year. It is not valid to calculate average behaviour over a time period, and then expect to encounter the same average in future time periods.
The market is different from a statistically stationary process, for example, flipping a fair coin or rolling dice. These stationary processes are the kind where you can calculate average behaviour and extrapolate to the future. The technique of averaging and extrapolating works, because you are always collecting data from the same unchanging process. Every time you flip the coin or roll the dice, it is the same coin or the same dice. Not so with the market. The market is always changing.
The illusion that markets are stationary is very dangerous, because it misleads inexperienced traders into thinking that they can make vast fortunes, when in fact, almost all of them lose. You will find lots of people who are trying to sell you something, by trying to convince you the market is stationary. You will also find lots of people who truly believe the market is stationary, because they don't know any better, and some of them will probably be very irritated by the suggestion that the market is not stationary.
Anyway, remember what the CFTC requires trading advisors to warn the public: "Past performance is no guarantee of future results."