There has recently been some discussion on the list about AD Model builder and the suitability of R for constructing the types of models used in fisheries management.
https://stat.ethz.ch/pipermail/r-help/2006-January/086841.html https://stat.ethz.ch/pipermail/r-help/2006-January/086858.html I think that many R users understimate the numerical challenges that some of the typical nonlinear statistical model used in different fields present. R may not be a suitable platform for development for such models. Around 10 years ago John Schnute, Laura Richards, and Norm Olsen with Canadian federal fisheries undertook an investigation comparing various statistical modeling packages for a simple age-structured statistical model of the type commonly used in fisheries. They compared AD Mdel Builder, Gauss, Matlab, and Splus. Unfortunately a working model could not be produced with Splus so its times could not be included in the comparison. It is possible to produce a working model with the present day version of R so that R can now be directly compared with AD Model Builder for this type of model. I have put the results of the test together with the original Schnute and Richards paper and the working R and AD Model Builder codes on Otter's web site http://otter-rsch.ca/tresults.htm The results are that AD Model builder is roughly 1000 times faster than R for this problem. ADMB takes about 2 seconds to converge while R takes over 90 minutes. This is a simple toy example. Real fisheries models are often hundred of times more computationally intensive as this one. Cheers, Dave ~ -- David A. Fournier P.O. Box 2040, Sidney, B.C. V8l 3S3 Canada Phone/FAX 250-655-3364 http://otter-rsch.com ______________________________________________ R-help@stat.math.ethz.ch 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.