PlanetMath (more info)
 Math for the people, by the people. Sponsor PlanetMath
Encyclopedia | Requests | Forums | Docs | Wiki | Random | RSS  
Login
create new user
name:
pass:
forget your password?
Main Menu
sections
Encyclopædia
Papers
Books
Expositions

meta
Requests (236)
Orphanage
Unclass'd (1)
Unproven (540)
Corrections (46)
Classification

talkback
Polls
Forums
Feedback
Bug Reports

downloads
Snapshots
PM Book

information
News
Docs
Wiki
ChangeLog
TODO List
Copyright
About
Owner confidence rating: High Entry average rating: No information on entry rating
statistics on PlanetMath (Topic)

This entry is supposed to become a textbook on statistics - or at least a guide to the statistics-related entries on PlanetMath. It will refer to related entries (e.g. from probability) that are not listed in the same MSC.

(This is currently a stub article. See also Textbook projects on PlanetMath.)



"statistics on PlanetMath" is owned by PrimeFan. [ full author list (2) | owner history (1) ]
(view preamble | get metadata)

View style:

Log in to rate this entry.
(view current ratings)

Cross-references: Textbook projects on PlanetMath, PlanetMath, statistics
There is 1 reference to this entry.

This is version 4 of statistics on PlanetMath, born on 2004-11-13, modified 2006-11-27.
Object id is 6474, canonical name is StatisticsOnPlanetMath.
Accessed 11755 times total.

Classification:
AMS MSC: 62-01 (Statistics :: Instructional exposition )
Pending Errata and Addenda
None.
[ View all 1 ]
Discussion
Style: Expand: Order:
forum policy

jump to page: 1 2 3 >> of 3 (13 items)

July Ponder This!!!!!!!!!!!!!! by PARASHAR on 2009-06-30 02:56:12
What is the probability that the last move in a backgammon (link - http://en.wikipedia.org/wiki/Backgammon) game will be a double? To make things easier, we assume that all the 15 checkers of each player are at their 1-point (just ready to bear-off); so each player, in its turn, removes (bear-off) two checkers for every non-double throw and four checkers for every double.

Hint: The solution is *not* the trivial 1/6.

http://en.wikipedia.org/wiki/Backgammon
[ reply | up ]
New Year Ponder This!!! by PARASHAR on 2009-01-04 23:46:02
Consider the following game. You have an opportunity to buy lottery tickets. Each ticket has a value t randomly and independently picked from the continuous and uniform distribution on the interval(0,1). Each ticket costs c (0<c<1). If you don't like the ticket you get you can throw it away and buy another one (at a cost of c). You can do this as often as you want. You can stop at any time and cash in the current ticket at which point the game ends. Your winnings are the value of the ticket you cashed less the cost of all the tickets you bought. You don't have to buy any tickets in which case your winnings are 0. If you adopt the best strategy what are your expected winnings as a function of c?

Suppose we modify the game so that you don't have to throw away any tickets. When you decide to stop buying tickets you can cash in any (but only one) of the tickets you have purchased and the game ends. Now what are your expected winnings (using the best strategy) as a function of c?

[ reply | up ]
Exciting Problem by PARASHAR on 2008-07-07 05:40:03
There is a very exciting problem at http://projecteuler.net/index.php?section=problems&id=202

Is any one interested in discussing that?
[ reply | up ]
grid by PARASHAR on 2008-06-26 05:31:07
You have a list of items you need to buy today, and you know the locations (represented as points on a cartesian grid) of a few stores in the area. You also know which of these stores are selling each item on your list, and at what price each store sells it. Given the price of gas, what is the minimum amount you need to spend in order to buy all the items on your shopping list and then drive back home? You start and end the journey at your house, which is located at (0,0).

To make matters interesting, some of the items on your list may be perishable. Whenever you make a purchase that includes one or more perishable items, you cannot drive to another store without first stopping back at your house. Every item on your shopping list is guaranteed to be sold by at least one store, so the trip will always be possible.

[ reply | up ]
June Ponder This by PARASHAR on 2008-06-03 07:49:20
This month's problems concern DNA testing. DNA tests can exclude people as the source of a DNA sample. Assume that the tests will never exclude the actual source but sometimes will fail to exclude someone who is not the actual source but who by chance happens to match the actual source at the DNA locations being tested.

1. Suppose before DNA testing we estimate X has p chance of being the actual source. Suppose there is a random match probability of 1/n. If testing does not exclude X what is our new estimate of the probability that X is the source?

2. Suppose we have a database of DNA data from k people. Suppose before comparing with the DNA sample we estimate that there is a chance p that the database contains the actual source and further that every person in the database is equally likely to be the actual source. Assume as above the random match probability for someone who is not the actual source is 1/n and that this probability is independent for multiple people who are not the actual source. Suppose we find exactly one person, X, in the database whose DNA matches the sample. What is our new estimate of the probability that the database contains the actual source (and therefore that the actual source is X).

3. In an actual case k was 338000 and the random match probability was said to be 1/1100000. Suppose we further assume (before checking) that there is a 20% chance that the actual donor is in the database and that everyone in the database is equally likely to be the actual donor. Suppose (as in the actual case) exactly one person, X, matching the sample is found in the database. Subject to the above assumptions, what is the probability that X is the actual donor? Give the probability rounded to four decimal places.

[ reply | up ]

jump to page: 1 2 3 >> of 3 (13 items)

Interact
post | correct | update request | add example | add (any)