[Basta-users] fitting a negative Gompertz to CR data

[Colchero, Fernando]

Hello Cliff,

   The only way I can imagine that you can do that without modifying the code is by using, for example, a Gompertz model with bathtub shape and setting the parameter arguments as follows:

   thetaStart = c(-1, 0.1, 0, -10000, 1e-10)
   thetaJump = c(0.01, 0.01, 0, 0, 0)

   This will force the model to set the 'adult' part of the model to 0 as well as the 'c' parameter, and only use the declining Gompertz to fit it. I'm not sure that this will actually work, but you can always give it a try. Still, the latest version of BaSTA should be able to retrieve parameters for a Gompertz with negative senescence. 

   Best,

   Fernando


______________________________________________
 
Fernando Colchero

Max Planck Institute for Demographic Research
Konrad Zuse Str. 1, 18057, Rostock, Germany
Tel:  +49 (0) 381 2081 113
Fax: +49 (0) 381 2081 529
E-mail: Colchero at demogr.mpg.de
______________________________________________





On Nov 15, 2011, at 4:07 PM, Cliff Cunningham wrote:


	Dear Basta,

	If I am applying Basta to a dataset, can I force it to fit a declining function, so that I can see the DIC and what it looks like? I assume it would be like the first part of the Siler function, which enforces a negative Gompertz, except this would apply to the whole dataset.

	Thanks!

	

	    Cliff Cunningham


	        Professor
	Biology Department
	     Duke University
	        130 Science Drive
	Durham NC 27708
	
	Phone 919-660-7356
	

	http://www.biology.duke.edu/cunningham




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