Notice this
You can not build a true random generator
Just better or worse simulators of random generation
Is a market system stocastic or chaotic ?
Subject to randomly generate shocks
Or simply a bunch of more or less bad random generators
Ie chaotic systems
Brock again
" The problem is that empirically it is hard to distinguish between
a stochastic system
and
chaos buffeted by noise. " " noise ??
Let's pretend he didn't add that ...
".....take a random number generator.
To test whether a random number generator is any good, e.g. whether it genera- tes numbers that are totally unpredictable, you can let it generate a series of drawings from a uniform(0,1) distribution. "
" If you plot xt against xt+1 with a series of 100,000 the unit square should fill up completely. "
"So the plot should look uniformly grey."
" But in practice, this kind of plots with drawings from a number generator will look like snowflakes."
" They will fill out the square, but you will see some patterns. "
" This means that some random number generators are lousy."
To continue this, you can add xt-1 and end up
with a cube. It is hard to draw a cube, but if you
are good, you can do so and you can see where the points lie in the cube.
If the generated num- bers kind of fill out the cube, without sub pat- terns, you have got a good random number ge- nerator.
But some will create patterns inside the cube which you can see with your naked eye.
This implies there is some kind of predictability. You can use xt and xt-1 to make a forecast about xt+1, so it is not random.
If the generated num- bers kind of fill out the cube, without sub pat- terns, you have got a good random number ge- nerator.
But some will create patterns inside the cube which you can see with your naked eye.
This implies there is some kind of predictability. You can use xt and xt-1 to make a forecast about xt+1, so it is not random.
In four dimensions you do not have the possi-
bility to draw a graph any longer. This is where
the BDS-test comes in. It tests whether there
are any patterns or clusters in higher and hi-
gher dimensional cubes. Working out the math
on that is quite challenging to say the least. So
the BDS-tests shows whether a series is sto-
chastic or deterministic by testing for any kind
of predictability in the series.