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Topic: ?Help with formula?
Replies: 2   Last Post: Jun 16, 1996 9:23 PM

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Eric Gindrup

Posts: 46
Registered: 12/8/04
Re: ?Help with formula?
Posted: Jun 15, 1996 12:21 AM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply wrote:
> OK, I need these:
> x 0 50 100
> f(x) oo 0 -oo (I switched the signs)
> Here's what I'm trying to do: I'm trying to measure "luck."
> If someone has a 25% chance of doing something (1/4 tries) and
> they succeed they should get rating R. If they have a 12.5%
> chance of succeeding (1/8 tries) then their rating should be
> 2R, double because it will only happen half as often. Likewise,
> something with a 6.25% chance would be 4R. I realized my
> previous table didn't work because a 16.67% event's R should be
> twice a 33.33% event's R and that didn't happen.

Up 'til now it sounds like R should be the number of expected
trials until success.

> A 50% event
> requires no luck at all and is therefore zero.

This however doesn't fit. It would mean R=0 in the above.

> There should be symmetry about (50, 0) and the function should
> be continuous. I know it will resemble sinh(), but that's when
> my brain started hurting. [...]

Gary S. Best

You should probably pick R to be the number of expected trials
until success. This gives you a function like:
f(0) = \infinity
f(.5) = 2
f(1) = 1
Or, if p is the probability of success, let f(p) = 1/p. This
function has the multiplicative property that you wanted.
-- Eric Gindrup !

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