Hi I'm trying to replicate Smith et al.'s (http://www.sciencemag.org/content/330/6008/1216.abstract) findings by fitting their Gompertz and logistic models to their data (given in their supplement). I'm doing this as I want to then apply the equations to my own data.
Try as a might, I can't quite replicate them. Any thoughts why are much appreciated. I've tried contacting the authors but I think they're away. The equations as I've used them are: log(mass)~log(K)-log(K/M)*exp(-a*t) and log(mass)~C*t^G The data file I've been using is attached. It starts at the K-Pg boundary with a body size of 3.3kg, following their description in the supplement. Their parameters and AICc values are given in their paper. I get something quite close for some of them (~0.245 G, their gamma, K estimates reasonable etc.), but in the logistic model C is more like 3 than 1.5, and the AICc values differ by ~10 rather than ~1. Cheers. Roland
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