R help - Nov 2007 - Algorithms for coincidences

I'm looking at algorithms for determining coincidences. In educational
testing, it is interesting to look at cheating via the birthday problem
where I can assess the probability of n students having the same test
score in a class of size k.

I was writing my own code for the b-day problem until I ran into the
qbirthday() function, which has solutions for the overflow problems I
kept running into. There is no "see also" part of this man page which
would reference me to other functions which may prove useful for such
problems. But, that doesn't mean they don't exist. 

I am just not familiar enough with this branch of mathematics to know
exactly what else I might look for. Does anyone know of any other R
functions that may be useful for me to look at in thinking about this
kind of problem? 

Harold

	[[alternative HTML version deleted]]

A paper that may help you:

"Methods for Studying Coincidences", Persi Diaconis; Frederick
Mosteller.  Journal of the American Statistical Association, vol 84, no.
408 (Dec., 1989), 853-861.

And remember that the birthday problem assumes independence, but if you
have 2 students that studied together (legitimately) then we would not
expect their scores to be independent.

Hope this helps,

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at intermountainmail.org
(801) 408-8111
 
 
> -----Original Message-----
> From: r-help-bounces at r-project.org 
> [mailto:r-help-bounces at r-project.org] On Behalf Of Doran, Harold
> Sent: Tuesday, November 06, 2007 12:10 PM
> To: r-help
> Subject: [R] Algorithms for coincidences
> 
> I'm looking at algorithms for determining coincidences. In 
> educational testing, it is interesting to look at cheating 
> via the birthday problem where I can assess the probability 
> of n students having the same test score in a class of size k.
> 
> I was writing my own code for the b-day problem until I ran into the
> qbirthday() function, which has solutions for the overflow 
> problems I kept running into. There is no "see also" part of 
> this man page which would reference me to other functions 
> which may prove useful for such problems. But, that doesn't 
> mean they don't exist. 
> 
> I am just not familiar enough with this branch of mathematics 
> to know exactly what else I might look for. Does anyone know 
> of any other R functions that may be useful for me to look at 
> in thinking about this kind of problem? 
> 
> Harold
> 
> 	[[alternative HTML version deleted]]
> 
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