Van K. Tharp mentioned there are 3 biases that will affect one’s trading:

1) Gambler’s fallacy bias

People tend to believe that after a string of losses, a win is going to come next. Take for example that you are playing a game of coin tossing with a capital of $1000. You lost 3 bets in a row on heads and cost you $100 each bet. What will you bet next and how much would you stake?

It is likely you will continue to bet on heads and with a higher stake, say $300. You do not ‘believe’ that it can be tails consistently. People fail to realize coin tossing is random and past results do not affect future outcomes.

Traders must treat each trade independently and not be affected by past results. It is important that your trading system tells you how much to stake your capital which is also known as position sizing, so that the risk-reward ratio will be optimal.

2) Limit profits and enlarge losses bias

People tend to limit their profits and give more room to losses. Nobody likes the feeling of losing. Most investors tend to hold on to losses and hope their investments will turn around soon, and they will be happy if their holdings break even. However, chances are that they will amount to greater losses. On the other hand, if they are winning, most investors tend to take profits early as they fear their profits will be wiped out soon. Thereafter, they regretted that they didn’t hold a little longer (sounds familiar?). (more…)