Hello! I am an 'R beginner'. I am trying to check if my data follow a negative binomial function. the command i've typed in is: > nbdo=rnegbin(58,mu=27.82759,theta=0.7349851) > ks.test(do$DO,nbdo) Each time i do that, p given is different and i get this warning message: 'Warning message: cannot compute correct p-values with ties in: ks.test(do$DO, nbdo) ' Could someone tell me what's wrong? What does 'with ties in' mean? Thank you! ------------------------------------------------------------------------------------------------------------------- Agn?s GAULT graduate student UMR 5173 MNHN-CNRS case postale 50 Species Conservation, Restoration and Population Survey (CERSP) 61 rue Buffon, 1er ?tage 75005 PARIS FRANCE Tel: 33 (0)1 40 79 57 64 Fax: 33 (0)1 40 79 38 35 Email: gault at mnhn.fr
help with kolmogorov smirnov test
3 messages · Agnes Gault, Uwe Ligges, James Reilly
Agnes Gault wrote:
Hello! I am an 'R beginner'. I am trying to check if my data follow a negative binomial function. the command i've typed in is:
> nbdo=rnegbin(58,mu=27.82759,theta=0.7349851) > ks.test(do$DO,nbdo)
Each time i do that, p given is different and i get this warning message: 'Warning message: cannot compute correct p-values with ties in: ks.test(do$DO, nbdo) ' Could someone tell me what's wrong? What does 'with ties in' mean?
If some values are duplicated, you have so called ties. Please read some textbook on this problem. This is not an R issue. Uwe Ligges
Thank you! ------------------------------------------------------------------------------------------------------------------- Agn?s GAULT graduate student UMR 5173 MNHN-CNRS case postale 50 Species Conservation, Restoration and Population Survey (CERSP) 61 rue Buffon, 1er ?tage 75005 PARIS FRANCE Tel: 33 (0)1 40 79 57 64 Fax: 33 (0)1 40 79 38 35 Email: gault at mnhn.fr
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Agnes Gault wrote:
Hello! I am an 'R beginner'. I am trying to check if my data follow a negative binomial function. the command i've typed in is:
> nbdo=rnegbin(58,mu=27.82759,theta=0.7349851) > ks.test(do$DO,nbdo)
Each time i do that, p given is different
The p-values are different each time because you are using a two-sample test, where one of the samples is randomly generated (and thus will be different each time). ks.test offers a one-sample test against a specified distribution, but this will still have problems with the ties. --- James Reilly Department of Statistics, University of Auckland Private Bag 92019, Auckland, New Zealand