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The Idiots Guide To Back Testing For Confidence
By: David Jenyns
After you`ve set your initial stop loss, chosen your method for calculating your
trailing stop loss, and implemented all your money management rules, there is
one last thing you should do; you should begin back testing your system.
With out back testing you will be headed in the right direction, but you won`t
know what to expect from your system. Back testing will also give you the
confidence to keep going when you begin to experience the doubt that every
trader faces at some time.
Back testing your system is by applying the rules and conditions of the system
to the stock`s historical market data. However, this is only possible if you`re
trading a system that is entirely mechanical and does not require any human
input to place the trades. How do you know whether or not your system is
completely mechanical for back testing? Can you take down your trading plan, the
set of rules and guidelines that you follow, and hand that over to someone else,
who could then trade the same system and receive the same results as you would
if they followed the system carefully?
If you can do this, you have a mechanical system that is ready for back testing.
If you can`t, you should look at implementing a completely mechanical system.
Perhaps one of the hardest parts in trading any system is to have the confidence
to stick with your system. In fact, a mechanical system almost forces you to
make decisions that are in direct conflict with what your gut feeling might tell
you to do.
Remember, our gut feeling tells us we should hold on to losing stocks until they
get to the break even point, and our gut feeling would tell us to sell shares as
soon as we`re a little bit in profit. Obviously, a mechanical system goes
against these human tendencies, and that is one of the reasons why it`s
psychologically difficult to trade. However, back testing a mechanical system,
will tell if you it your plan will work or not.
While back testing will not tell you with 100% accuracy what the profitability
of your system will be once you start trading it, it will give you a very good
sense of what you can expect. All prices are driven by the same two factors,
supply and demand, in the present and in the past. So, even though price
movements are never going to be exactly the same, in your back testing you will
see the patterns, and similar movements that show up over time. With back
testing you can discover the how profitable you system is likely to be, and how
often you are likely to have a loss rather than a profit.
Back testing your system over different market conditions, it can be reasonable
to draw parallels as to the performance of your system historically to its
performance trading it in real time. Knowing this, because of back testing, will
make it much easier to stick with your system, and the profits you can
realistically skyrocket.
About the Author:
David Jenyns, leading expert in designing profitable trading systems, MetaStock
website offers a huge free collection of trading related tips and tricks.
http://www.meta-formula.com/subscribe
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