From: Aswad Gurjar <aswadgurjar_at_gmail.com>

Date: Sun, 10 Feb 2008 12:56:26 +0530

Warning message:

Chi-squared approximation may be incorrect in: summary.goodfit(gf)

R-help_at_r-project.org mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Sun 10 Feb 2008 - 07:29:17 GMT

Date: Sun, 10 Feb 2008 12:56:26 +0530

Hello,

Thank You for response.Yes,It is discrete data.I have tried discrete model
using goodfit() test.But that too is not working.Is there any other test for
discrete data?

When I try goodfit() test for discrete distribution:

gf<-goodfit(x[[1]],type= "nbinomial",method= "MinChisq")
where x[[1]] is my data with 9 bins.

x contains following data and interval is of 2800 seconds:

V1

1 0

2 127

3 477

4 363

5 685

6 0

7 363

8 0

9 0

I get following errors:

Warning messages:

1: NaNs produced in: pnbinom(q, size, prob, lower.tail, log.p) 2: NaNs produced in: pnbinom(q, size, prob, lower.tail, log.p) 3: NaNs produced in: pnbinom(q, size, prob, lower.tail, log.p) 4: NaNs produced in: pnbinom(q, size, prob, lower.tail, log.p) 5: NaNs produced in: pnbinom(q, size, prob, lower.tail, log.p) 6: NaNs produced in: pnbinom(q, size, prob, lower.tail, log.p) 7: NaNs produced in: pnbinom(q, size, prob, lower.tail, log.p)

summary(gf)

Goodness-of-fit test for nbinomial distribution

When i use poisson distribution :

gf<-goodfit(x[[1]],type= "poisson",method= "MinChisq")

Goodness-of-fit test for poisson distribution

X^2 df P(> X^2) Pearson 4.137318e+138 3 0

Warning message:

Chi-squared approximation may be incorrect in: summary.goodfit(gf)

What should i do now?How can I remove these warnings and errors? Thank You.

Aswad

On 2/10/08, Bill.Venables_at_csiro.au <Bill.Venables_at_csiro.au> wrote:

*>
*

> Chenge your model, most likely.

*>
**> You are telling us a) the response is discrete and b) there is a
**> substantial probability that the value is zero. The gamma distributon
**> is a model for a continuous response, your response is integer valued.
**> Perhaps you should consider something the Poisson or Negative Binomial.
**>
**> Evem from the little you give us, the problem seems more statistical
**> than computational to me.
**>
**>
**> Bill Venables
**> CSIRO Laboratories
**> PO Box 120, Cleveland, 4163
**> AUSTRALIA
**> Office Phone (email preferred): +61 7 3826 7251
**> Fax (if absolutely necessary): +61 7 3826 7304
**> Mobile: +61 4 8819 4402
**> Home Phone: +61 7 3286 7700
**> mailto:Bill.Venables_at_csiro.au
**> http://www.cmis.csiro.au/bill.venables/
**>
**> -----Original Message-----
**> From: r-help-bounces_at_r-project.org [mailto:r-help-bounces_at_r-project.org]
**> On Behalf Of Aswad Gurjar
**> Sent: Sunday, 10 February 2008 4:17 PM
**> To: r-help_at_r-project.org
**> Subject: [R] Error in optim while using fitdistr() function for
**> estimationof parameters
**>
**> Hello,
**>
**> I am trying to fit distribution for data consisting of 421 readings.It
**> is
**> basically no of requests arrived per minute.It contains many 0 entries
**> as no
**> of requests.When i use
**> fd<-fitdistr(V2,"gamma")
**> I get following error:
**> Error in optim(x = c(0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L, 0L,
**> :
**> initial value in 'vmmin' is not finite
**>
**> What should I do ? I need this function because I want to get value of
**> estimated parameters.
**> Is there any other function to perform such calculations?
**> Please help me.
**> Thank You.
**>
**> Code is as follows:
**> x<-data.frame()
**> N<-data.frame((read.table("cs2ip.txt")))
**> attach(N)
**> library(MASS)
**> fd<-fitdistr(V2,"gamma")
**>
**> Aswad
**>
**> [[alternative HTML version deleted]]
**>
**> ______________________________________________
**> R-help_at_r-project.org mailing list
**> **https://stat.ethz.ch/mailman/listinfo/r-help
**> PLEASE do read the posting guide
**> http://www.R-project.org/posting-guide.html
**> and provide commented, minimal, self-contained, reproducible code.
**>
**>
**>
*

[[alternative HTML version deleted]]

R-help_at_r-project.org mailing list

https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Sun 10 Feb 2008 - 07:29:17 GMT

Archive maintained by Robert King, hosted by
the discipline of
statistics at the
University of Newcastle,
Australia.

Archive generated by hypermail 2.2.0, at Sun 10 Feb 2008 - 11:30:13 GMT.

*
Mailing list information is available at https://stat.ethz.ch/mailman/listinfo/r-help.
Please read the posting
guide before posting to the list.
*