# Bayesian ranking

Hi Experts,

Please refer to the web page http://en.wikipedia.org/wiki/TrueSkill

What I would like to know is what does the following mean?

"As such N(x) can be interpreted as the probability that the player's "true" skill is x."

If my Mu is 25 and my Sigma is 3 how are these values used in the above to give my skill?
###### Who is Participating?

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Commented:
if your Mu is 25 and your Sigma is 3, then the probability that your true skill is between x0 and x1 is
(erf((x1-25)/(3sqrt2))-erf((x0-25)/(3sqrt2)))/2
e.g. there would be a 0.683 probability that your true skill is between 22 and 28
0

Experts Exchange Solution brought to you by

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Author Commented:
Hi Ozo,

How do I calculate the error function?
What does 3sqrt2 mean?
Where do the values of X0 and X1 come from?
Can I work out the X0 and X1 values for a given probability of say 99%?
0
Commented:
See, for example, http://en.wikipedia.org/wiki/Normal_distribution
A 99% confidence interval would be about 2.6 sigma, or 25±7.7
0
Author Commented:
Hi Ozo,

What does 3sqrt2 mean?
How do I calculate erf?
0
Commented:
Sigma * square root of 2
Usually one would look up values in a table, or use one of the formulas referenced at links like the above.
0
###### It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Math / Science

From novice to tech pro — start learning today.