

It's not exponential, it's sigmoidal - terpua
http://radar.oreilly.com/archives/2007/11/sigmoidal_not_exponential.html

======
jacobolus
Except that's a silly distinction, when you don't yet have any information
about what the upper bound is, or any evidence that growth is slowing from its
exponential stage. The growth of real-world things clearly has some upper
bound, and in saying that it's "exponential" this is understood by all
listeners.

Since calling a real-world trend "exponential growth" is always an
approximation, pointing out that it's actually "approximately sigmoidal
growth, i.e. only approximately exponential until it flattens out sometime in
the eventual future" is (you guessed it) a redundant waste of breath.

And to say that pointless pedantry is the same as "mathematical literacy" is
even sillier.

~~~
pixcavator
Even so, you can't argue that the growth is exponential by simply looking at
the graph. It could just as well be polynomial. To conclude that it is
exponential you need some kind of analysis, like "every user brings two, those
bring two each etc".

~~~
sethjohn
I believe this article is referencing the the metaphor and the hyperbole of
"Exponential Growth!!!"...not a mathematical treatment of growth rates.

That growth eventually slows is a very very simple point, but it's important
to never forget. Maybe everybody is making this too complicated because Saul
Griffith is supposed to be a 'genius' now?

------
henning
"And as Saul noted a few moments later, most of these curves aren't even
sigmoidal, they are sinusoidal. (This is, incidentally, why Ray Kurzweil is
most likely wrong about the singularity.)"

Am I the only one who gets tired of sweeping bullshit generalizations like
this? I can't believe people will pay to hear this kind of nonsense.

He isn't actually saying anything you can rebut.

------
ceesai
Modding this up is an even truer sign of mathematical illiteracy. The sigmoid
itself contains an exponent that is damped at higher values. One could go
further and say that it is not even a sigmoid because all web traffic will
peter off eventually, with the eventuality in the undefined horizon. Does
anyone really assume an exponential growth in the literal sense with users
rushing in via some inter-galactic network when all earth users are exhausted?

~~~
jimbokun
"Does anyone really assume an exponential growth in the literal sense with
users rushing in via some inter-galactic network when all earth users are
exhausted?"

Some valuations for .com companies at the end of the 20th century did seem to
have factored this expectation into their analysis.

