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How to calculate chi-square statistic for a distribution
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Silas Adiko
May 21, 2013, 2:45:10 PM5/21/13
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Dear Support,
I am fitting a distribution to data and trying to perform chi-square goodness-of-fit test.
I have calculated the likelihood values and wanted to perform goodness-of-fit test
However, having read through the Help menus, I tried to run the script below but am getting error:
x=claims; [h,p,stats] = chi2gof(X,'cdf','weibull',nparams,2)
where claims is 1xn vector
I do not know where I have gone wrong and would appreciate anyone's assistance to resolve this.
Also, I needed the script to calculate chi-square test statistic for Negative Binomial distribution.
Much thanks in advance
I am fitting a distribution to data and trying to perform chi-square goodness-of-fit test.
I have calculated the likelihood values and wanted to perform goodness-of-fit test
However, having read through the Help menus, I tried to run the script below but am getting error:
x=claims; [h,p,stats] = chi2gof(X,'cdf','weibull',nparams,2)
where claims is 1xn vector
I do not know where I have gone wrong and would appreciate anyone's assistance to resolve this.
Also, I needed the script to calculate chi-square test statistic for Negative Binomial distribution.
Much thanks in advance
Steven_Lord
May 21, 2013, 5:43:37 PM5/21/13
to
"Silas Adiko" <s_a...@yahoo.co.uk> wrote in message
news:kngfbm$qb4$1...@newscl01ah.mathworks.com...
> Dear Support,
This is not the official Technical Support group. If you're looking for
official support, see the instructions in my signature.
> I am fitting a distribution to data and trying to perform chi-square
> goodness-of-fit test.
>
> I have calculated the likelihood values and wanted to perform
> goodness-of-fit test
>
> However, having read through the Help menus, I tried to run the script
> below but am getting error:
>
> x=claims; [h,p,stats] = chi2gof(X,'cdf','weibull',nparams,2)
>
> where claims is 1xn vector
>
> I do not know where I have gone wrong and would appreciate anyone's
> assistance to resolve this.
My guess is that it is "Undefined function or variable 'X'." Remember that
in MATLAB, the variable x is NOT the same as the variable X.
If that is not the error you received, post the full text of the message to
the newsgroup (please do NOT email it to me directly) and someone may be
able to offer a suggestion.
*snip the other question; I don't know the answer off the top of my head*
--
Steve Lord
sl...@mathworks.com
To contact Technical Support use the Contact Us link on
http://www.mathworks.com
Tom Lane
May 21, 2013, 6:13:04 PM5/21/13
to
>> x=claims; [h,p,stats] = chi2gof(X,'cdf','weibull',nparams,2)
...
> My guess is that it is "Undefined function or variable 'X'." Remember that
> in MATLAB, the variable x is NOT the same as the variable X.
Two other things likely have caused you problems:
> in MATLAB, the variable x is NOT the same as the variable X.
1. Use @wblcdf or 'wblcdf' rather than 'weibull'
2. Use 'nparams' rather than nparams
-- Tom
Silas Adiko
May 22, 2013, 7:03:09 PM5/22/13
to
"Tom Lane" <tl...@mathworks.com> wrote in message <kngrhg$6am$1...@newscl01ah.mathworks.com>...
Dear Steve and Tom.
I have carried out your suggestions but none of them worked.
Below are the scripts and the full error texts:
X=claims;
[h,p,stats] = chi2gof(X,cdf,'weibull',nparams,2)
??? Error using ==> cdf at 49
Not enough input arguments
>> [h,p,stats] = chi2gof(X,cdf,'weibull','nparams',2)
??? Error using ==> cdf at 49
Not enough input arguments
>> [h,p,stats] = chi2gof(X,@wblcdf,'weibull','nparams',2)
??? Error using ==> chi2gof at 137
Parameter name must be text.
>> [h,p,stats] = chi2gof(X,'@wblcdf','weibull','nparams',2)
??? Error using ==> chi2gof at 137
Invalid parameter name: @wblcdf.
>> [h,p,stats] = chi2gof(X,cdf,'@wblcdf','nparams',2)
??? Error using ==> cdf at 49
Not enough input arguments
>> [h,p,stats] = chi2gof(X,cdf,'wblcdf','nparams',2)
??? Error using ==> cdf at 49
Not enough input arguments
2. Also, I needed the script to calculate chi-square statistic for Negative Binomial Distribution.
I appreciate your assistance very much.
Silas
I have carried out your suggestions but none of them worked.
Below are the scripts and the full error texts:
X=claims;
[h,p,stats] = chi2gof(X,cdf,'weibull',nparams,2)
??? Error using ==> cdf at 49
Not enough input arguments
>> [h,p,stats] = chi2gof(X,cdf,'weibull','nparams',2)
??? Error using ==> cdf at 49
Not enough input arguments
>> [h,p,stats] = chi2gof(X,@wblcdf,'weibull','nparams',2)
??? Error using ==> chi2gof at 137
Parameter name must be text.
>> [h,p,stats] = chi2gof(X,'@wblcdf','weibull','nparams',2)
??? Error using ==> chi2gof at 137
Invalid parameter name: @wblcdf.
>> [h,p,stats] = chi2gof(X,cdf,'@wblcdf','nparams',2)
??? Error using ==> cdf at 49
Not enough input arguments
>> [h,p,stats] = chi2gof(X,cdf,'wblcdf','nparams',2)
??? Error using ==> cdf at 49
Not enough input arguments
2. Also, I needed the script to calculate chi-square statistic for Negative Binomial Distribution.
I appreciate your assistance very much.
Silas
Silas Adiko
May 22, 2013, 8:35:09 PM5/22/13
to
"Silas Adiko" wrote in message <knjird$o58$1...@newscl01ah.mathworks.com>...
I am happy to inform you that I found a solution while still searching on google . The link is http://ocw.mit.edu/courses/mathematics/18-443-statistics-for-applications-fall-2006/lecture-notes/lecture11.pdf.
Thank you all very much.
Silas
> "Tom Lane" <tl...@mathworks.com> wrote in message <kngrhg$6am$1...@newscl01ah.mathworks.com>...
> > >> x=claims; [h,p,stats] = chi2gof(X,'cdf','weibull',nparams,2)
> > ...
> > > My guess is that it is "Undefined function or variable 'X'." Remember that
> > > in MATLAB, the variable x is NOT the same as the variable X.
> >
> > Two other things likely have caused you problems:
> >
> > 1. Use @wblcdf or 'wblcdf' rather than 'weibull'
> > 2. Use 'nparams' rather than nparams
> >
> > -- Tom
> Hello Steve & Tom,
> > >> x=claims; [h,p,stats] = chi2gof(X,'cdf','weibull',nparams,2)
> > ...
> > > My guess is that it is "Undefined function or variable 'X'." Remember that
> > > in MATLAB, the variable x is NOT the same as the variable X.
> >
> > Two other things likely have caused you problems:
> >
> > 1. Use @wblcdf or 'wblcdf' rather than 'weibull'
> > 2. Use 'nparams' rather than nparams
> >
> > -- Tom
I am happy to inform you that I found a solution while still searching on google . The link is http://ocw.mit.edu/courses/mathematics/18-443-statistics-for-applications-fall-2006/lecture-notes/lecture11.pdf.
Thank you all very much.
Silas
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