Jun 24, 2015
One of the most important concepts to grasp is that successful traders tend to think in terms of trading probabilities. The trouble is and this is obvious by
the rate of attrition, most either dont get this or even attempt to address it.
So the thing to really think about here is the nature of an edge. I’m not
talking about the technical specifics of an edge – I’m talking about what it
gives you in terms of trading advantage.
Simply put, an edge is a higher probability of a certain outcome over
another, given a certain set of circumstances on a historical set of
trades. Note the all-important historical basis.
This means that the market has behaved in a certain way in the past and therefore the edge does nothing more than indicate the chances of it happening again in the future. The
markets are ever-evolving and so you cannot ever rely on a trade working
forever.
The fact that markets are always changing also gives rise to the idea
that no single trade is the same. What the market has done prior to the setup
will impact upon it. Which market participants are currently present and
active will also have an effect.
No trade is ever precisely the same even if it looks like another – so the
assumption has to be that the outcome may well be different.
As much as humans are pattern recognition machines and at times can
get a really good feel for what’s happening in the market, you just don’t know what will happen next.
For example, a massive fund might enter the market and need to sell a gazillion contracts when you’re in a
long position.
The same fund might have a trader who “fat fingers” (fat finger = the act
of accidentally inputting a trade incorrectly – sometimes placing a
much larger trade than intended) and price might move sharply against you.
Or even a piece of news might come out that has a dramatic impact on
prices.
None of these things is predictable in nature and so whatever the market and your trade looks like, you just
don’t know for certain how it will turn out.
Going back to the definition of an edge, you’ll note that I say over a
historical set of trades. The implication is that an edge won’t necessarily play
out over a single or even small number of trades whatever the outcome – it requires many trades to be taken to get close to the historical win rate
The outcome of a single trade is either a winner or a loser and it’s not
something you either want or even need to predict.
Take the probability of heads on the flip of a coin as an example. Over 10 trades you might get 5 heads, but it’s
just as conceivable that you get 3 heads, 7 heads or even 0 heads.
Now if you went on to flip the coin 100 or 1000 times, the rate of heads you’ll
achieve will most likely come closer and closer to the theoretical odds of a
head.
The same principle applies for casinos. They know that the odds are in their favor and for those odds to play out, they need to keep taking your bets
over and over and over again. So a big winner can actually help them by
encouraging more bets.
If a setup fulfills the criteria of your edge, how do you know if it will fall
into the winning or losing category? If you knew it would be a loser, why would you even bother taking it?
We’ve established that there are plenty of uncertainties in trading and because of this, it’s important to not only think but also trade in terms of
probabilities.
In order to do so, it’s absolutely crucial to know exactly what your edge is and what needs to happen in order for you
to take or exit the trade.
By making things as unambiguous as possible, you are able to replicate your own actions given certain observations in an otherwise imperfect market – or at the very least, you know what you
should be doing.
Taking a winner or a loser on a single trade should be almost irrelevant
when trading probabilities.