date: Thu, 5 Jun 1997 11:17:45 -0400 from: drdendro@ldgo.columbia.edu (Edward R. Cook) subject: Re: Your paper to: Keith Briffa Hi Keith, One would think that your paper would be a slamdunk. But we all know how incredibly fickle Nature is. I got a call from Philip Newton (no doubt Isaac's direct lineal descendent. Nature wouldn't have it any other way!). He asked me to review a 2-page comment-style submission on Bayesian regression methods applied to tree-ring analysis. I wonder if it is from Van Deusen. He is the only one who has ever played with that stuff with tree rings. Seems the tone of the comment is that tree-ring scientists have been getting it wrong for all these years by using standard OLS. I'll let you know what it says when I get it. Ken is working on a general non-linear regression routine for fitting non-linear growth models to tree-ring series. He is generalizing the Hugershoff and general exponential models to allow for a positive asymptote, like the modified neg expon curve, and for allowing for an offset from the origin. As it stands now, the Hugerhoff and gen expon models assume that the first ring is formed at year t=1. We know that this is not the case in almost all cases. How it will all work in practice is yet to be seen. I also found an error in the modified negative exponential curve routine in the Tucson DPL version of ARSTAN. Seems it would not iterate properly and kicked out too quickly often giving near-linear fits to exponential growth trends. I validated it, with the help of Dave Meko, with 6 independent programs like MATLAB, SPSS, and Kaleidagraph. So, I sent my Fortran code to Richard and the error has been corrected. The corrected version of DPL ARSTAN is now on the Tucson ftp site. If you or anyone else uses it, please tell them. Henri suggested that I put out a notice on the forum, but I reckon that that is something that Tucson should do. Afterall, it's their baby ... with a few birth defects. I have been able to change my schedule and flight for Australia, so now I can make the session. I haven't hear from Phil yet on this, but I guess he will be pleased. Cheers, Ed