[R] named list 'start' in fitdistr

[vincent.stoliaroff@sgcib.com]

Oups! I should have read further the help file...

Thank you very much



|---------+---------------------------->
|         |           spencer.graves at PD|
|         |           F.COM            |
|         |                            |
|         |           07/25/03 05:02 PM|
|         |                            |
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  |                                                                                                                              |
  |       To:       Vincent STOLIAROFF/fr/socgen at socgen                                                                          |
  |       cc:       r-help at stat.math.ethz.ch                                                                                     |
  |       Subject:  Re: [R] named list 'start' in fitdistr                                                                       |
  >------------------------------------------------------------------------------------------------------------------------------|




An example in help(fitdistr) (R 1.7.1 for Windows) is "fitdistr(x,
dgamma, list(shape = 1, rate = 0.1), lower = 0.01)".  Based on this,
have you tried the following:

 >>fitdistr(test,"lognormal", start=list(meanlog=0, sdlog=1))

hope this helps.  spencer graves

vincent.stoliaroff at sgcib.com wrote:
> Hi R lovers!
>
> I'd like to know how to use the parameter 'start' in the function
> fitdistr()
> obviously I have to provide the initial value of the parameter to
optimize
> except in the case of a certain set of given distribution
>
>
> Indeed according to the help file for fitdistr
> "     For the following named distributions, reasonable starting values
>      will be computed if `start' is omitted or only partially
>      specified: `cauchy', `gamma', `logistic', `negative binomial' (R
>      only, parametrized by `mu' and `size'), `t', `uniform', `weibull'.
"
>
>
> However I cannot fit an univariate distribution named 'test'
>
> I get this:
>
>
>>fitdistr(test,"lognormal")
>
> Error in fitdistr(test, "lognormal") : `start' must be a named list
>
>
>>fitdistr(test,"lognormal",start$meanlog=0,start$sdlog=1)
>
> Error: syntax error
>
> How I am supposed to type a value for start depending on the distribution
> on which I am fitting my set
>
> thanks
>
>
>
>
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