Anyone who has been
forced to take Statistics 101 in high school or in college has
probably been exposed to a discussion of the odds of getting a
head or a tail when flipping a coin. Extensive experiments have
documented that no matter how many times you flip a coin, there
is always a 50-50 chance of getting a head or a tail. If you toss
ten straight heads in a row, you still have a 50-50 chance of getting
a head on the eleventh try.
This axiom is the cornerstone for the
concept of normal distribution of random events. For example, let’s
flip a penny 225 times — 15
separate series of 15 tosses each. The theoretical results follow:
| Series |
Results:
|
| |
#Heads |
#Tails |
| 1 |
1 |
14 |
| 2 |
2 |
13 |
| 3 |
3 |
12 |
| 4 |
6 |
9 |
| 5 |
8 |
7 |
| 6 |
7 |
8 |
| 7 |
10 |
5 |
| 8 |
11 |
4 |
| 9 |
9 |
6 |
| 10 |
5 |
10 |
| 11 |
6 |
9 |
| 12 |
4 |
11 |
| 13 |
2 |
13 |
| 14 |
1 |
14 |
| 15 |
0 |
15 |
|
Each
time this experiment is repeated, the results may or may not be
repeated. However, the majority of time, very similar results
will result.
Specifically, the results most often — assuming
the coin used is properly balanced – will be in the middle
of the spectrum. It would be very unusual (32,000:1) to get 15 straight
heads or tails,
or only one or two tails and the rest heads, or all heads and no
tails. Normal distribution describes what is likely to occur when
random events occur. Charting this on a graph generates the well-known
bell-shaped curve.
An additional assumption is made, namely that
when the normal distribution concept is applied to the “random
price action,” one
needs to use lognormal distribution. This skews the results to
the positive side of the mean to account for inflation and the
unlikely
event of a commodity price going to zero. Making this adjustment
to the curve produces a bell-shaped curve leaning slightly to the
right.
The bell-shaped curve is the distribution
curve. The one produced by flipping a coin repeatedly is “normal” or
moderate in appearance, but the shape can change. Erratic data
produces a
flat arc because the data points are scattered. Data representing
a slow moving futures market result in a curve that is very steep
or narrow, since the data points are close together.
The key concept
is that the flatter the shape of the distribution curve, the more
volatile is the market being evaluated. Plotting
price changes for various markets to generate distribution curves
is important so traders can quantify market volatility. Once this
is done, it gives traders the ability to make statistically valid
estimates of what price moves can be expected from these markets.
Underline
the words “statistically valid estimates of what
can be expected.” This is the best a trader can do when he
is attempting to forecast futures prices. On average, or normally,
he will be correct, but this doesn’t guarantee that he will
always be right. It’s inevitable that he will still experience
losses.
Hopefully, it will put the odds in the trader’s
favor, giving him an edge. It should provide an excellent insight
into
market
volatility, allowing him to answer questions like:
How much of a
price move can I expect?
What are the chances of this market making
a limit move?
Can I expect a certain futures or stock to
make enough of a move during the life of the option I plan to buy
to make a
profit on
the option?
This type of analysis provides educated guesses
to these questions. It is the basis behind the computer programs
that calculate
the
theoretic value of options, as an example. By running these formulas,
the programs
rank the option alternatives telling traders which ones are underpriced
or overpriced.
What this analysis does not do is tell us
which way a market will move. Don’t forget, we are discussing
volatility of what has been classified as RANDOM moving markets.
The trader
should be able
to figure the statistical odds of a market making a $2.00 move
over the next 35 days — but will it be up or down?
But that
information won’t come from this type of analysis.
The answer – or, more correctly, the best estimate — must
come from other types of analysis, such as fundamental or technical.
Once
a trader has an opinion of whether he is facing a bull or bear
move, he turns to volatility research to determine the expected
volatility
of the market(s) under consideration.
The next step is to calculate
the probability of the anticipated price projections.
The distribution
curve provides a graphic representation of the distribution of
random price action. It is now necessary to
quantify the data
so projections can be made. |