Probable spammer Re: Problems with nls

It appears to me that rahul143 is a spammer who has automatated  
extraction of old posts to Nabble as a way of delivering  
advertisements. This is an exact copy of a posting to Nabble on
Mar 28, 2011; 2:33pm  Worik StantonSullivan, Timmerman and White  
1999: TA rules, and R
[Apologies if I have sent this multiple times.  I have been struggling
with SMTP sewrvers and I have not seen my message appear on the list]

Friends

I am trying to save myself some tedious work.

I am processing a paper from  "The Journal Of Finance * Vol. LIV,  
No. 5
October 1999" by Sullivan,  Timmerman and  White.  "Data-Snooping,
Technical Trading Rule Performance, and the Bootstrap"
This is not the only instance of his postings being identical to old  
questions.

Here is another (and I suspect with diligent search all of them might  
have been constructed the same way.)
:
Mar 28, 2011; 2:33pm  Worik StantonSullivan, Timmerman and White  
1999: TA rules, and R
[Apologies if I have sent this multiple times.  I have been struggling
with SMTP sewrvers and I have not seen my message appear on the list]

Friends

I am trying to save myself some tedious work.

I am processing a paper from  "The Journal Of Finance * Vol. LIV,  
No. 5
October 1999" by Sullivan,  Timmerman and  White.  "Data-Snooping,
Technical Trading Rule Performance, and the Bootstrap"
My advice is to divert his postings to your trash bin until his Nabble  
account can be shut down.
David.

On Dec 2, 2012, at 7:33 AM, rahul143 wrote:

> I'm trying to fit the Bass Diffusion Model using the nls function in  
> R but
> I'm running into a strange problem. The model has either two or three
> parameters, depending on how it's parameterized, p (coefficient of
> innovation), q (coefficient of immitation), and sometimes m (maximum  
> market
> share). Regardless of how I parameterize the model I get an error  
> saying
> that the step factor has decreased below it's minimum. I have tried
> re-setting the minimum in nls.controls but that doesn't seem to fix  
> the
> problem. Likewise, I have run through a variety of start values in  
> the past
> few days, all to no avail. Looking at the trace output it appears  
> that R
> believes I always have one more parameter than I actually have (i.e.  
> when
> the model is parameterized with p and q R seems to be seeing three
> parameters, when m is also included R seems to be seeing four). My
> experience with nls is limited, can someone explain to me why it's  
> doing
> this? I've included the data set I'm working with (published in  
> Michalakelis
> et al. 2008) and some example code.
>
> ## Assign relevant variables
> adoption <-
> c 
> (167000,273000,531000,938000,2056452,3894103,5932090,7963742,9314687,10469060,11393302,11976340 
> )
> time <- seq(from = 1,to = 12, by = 1)
> ## Models
> Bass.Model <- adoption ~ ((p + q)^2/p) * (exp(-(p + q) * time)/((q /  
> p) *
> exp(-(p + q) * time) + 1)^2)
> ## Starting Parameters
> Bass.Params <- list(p = 0.1, q = 0.1)
> ## Model fitting
>
>
>
> -----
> TO GET MORE DETAILS CLICK HERE
> --
> View this message in context: http://r.789695.n4.nabble.com/Problems-with-nls-tp4651641.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> 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.

David Winsemius, MD
Alameda, CA, USA

Probable spammer Re: Problems with nls

Thread (3 messages)