Re: NT4-SP3 Sequence Prediction

[zeus () SHELL ACADIACOM NET (Mark Gansle)]

On Wed, 9 Sep 1998 nate () ROOT ORG wrote:

> It is very easy.  Assume that you have a standard deviation of 3 in the
> sequence every 10 ms (Ivan Arce measured a stdev of 2.6942).  This means
> that a single guessed sequence of 499, 500, or 501 has a ~68% (1 stdev)
> chance of being correct. Assuming you are guessing one every 10 ms, it
> would only take 3 tries (30 ms) for you to have a better than 90% chance
> of succeeding.

Just as a point of order, ~68% would fall between 496 and 502, assuming a
bell-shaped curve.  Your numbers fell within a one-standard-deviation
interval, and 68% fall within one standard deviation (plus or minus) of
the mean (499, according to Ivan).  Plus, I'd wonder if the distribution
is truly bell-shaped.

Regardless of this point, your argument is still valid.  Chebysev's
theorem tells us that at least 75% would fall within a 12-unit interval,
which means that this is open to a not-so-brute force attack.

Mark Gansle