R help - Sep 2015 - How to do global curve fitting in R

Hello all,

I am trying to fit my data to a nls model. I have many sets of data
and each can fit well for the curve. but I want to fit them at once by
sharing 2 of 3 parameters of the model. I know it is a typical global
curve fitting problem, but I don't know how to do it by R?

Does anyone know any package for this??

Thanks a lot!


Julian

Jianling:

1. What models are you trying to fit? Details matter, and it is
impossible to give a good answer without specifics.

2. In general terms, to do this one combines all the data and allows
for "appropriate" changes in the model parameters for the different
groups. For example, different intercepts, rate constants, etc. This
is where the specifics matter.

3. This is really more a statistics than an R question, and you would
probably do better to pursue these issues either with a local
statistical resource or on a statistics site, like
stats.stackexchange.com.

Cheers,
Bert
Bert Gunter

"Data is not information. Information is not knowledge. And knowledge
is certainly not wisdom."
   -- Clifford Stoll


On Wed, Sep 9, 2015 at 9:04 AM, Jianling Fan <fanjianling at gmail.com>
wrote:
> Hello all,
>
> I am trying to fit my data to a nls model. I have many sets of data
> and each can fit well for the curve. but I want to fit them at once by
> sharing 2 of 3 parameters of the model. I know it is a typical global
> curve fitting problem, but I don't know how to do it by R?
>
> Does anyone know any package for this??
>
> Thanks a lot!
>
>
> Julian
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.

Hi, Bert

Thanks for your reply.

I am fitting a logistic does response model with 3 parameters as :
y=a/(1+(x/x0)b), I have many sets of data. I can fit each of them for
the model. but I want them shared the parameter x0 and b, but varied
for each a.

I don't think it is a  statistics problem. It is a typical global
curve fitting problem with shared parameters. And I know how to do it
by many other software. But since I am trying to use R, I am wondering
is there any package or method to do it in R?

Thanks!

Jianling


On 9 September 2015 at 10:16, Bert Gunter <bgunter.4567 at gmail.com>
wrote:
> Jianling:
>
> 1. What models are you trying to fit? Details matter, and it is
> impossible to give a good answer without specifics.
>
> 2. In general terms, to do this one combines all the data and allows
> for "appropriate" changes in the model parameters for the
different
> groups. For example, different intercepts, rate constants, etc. This
> is where the specifics matter.
>
> 3. This is really more a statistics than an R question, and you would
> probably do better to pursue these issues either with a local
> statistical resource or on a statistics site, like
> stats.stackexchange.com.
>
> Cheers,
> Bert
> Bert Gunter
>
> "Data is not information. Information is not knowledge. And knowledge
> is certainly not wisdom."
>    -- Clifford Stoll
>
>
> On Wed, Sep 9, 2015 at 9:04 AM, Jianling Fan <fanjianling at
gmail.com> wrote:
>> Hello all,
>>
>> I am trying to fit my data to a nls model. I have many sets of data
>> and each can fit well for the curve. but I want to fit them at once by
>> sharing 2 of 3 parameters of the model. I know it is a typical global
>> curve fitting problem, but I don't know how to do it by R?
>>
>> Does anyone know any package for this??
>>
>> Thanks a lot!
>>
>>
>> Julian
>>
>> ______________________________________________
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> 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.


-- 
Jianling Fan
???