[Basta-users] Negative senescence when enforced!

[Colchero, Fernando]

Hi Cliff,

   Thanks for the update! You can simulate a dataset of ages at death from a Gompertz mortality (mu(x) = a * exp(b * x)) with the following code:

rgomp     = function(n, theta) {
  u      = runif(n)
  rx     = log(1 - log(1 - u) * theta[2] / exp(theta[1])) / theta[2]
  return(rx)
}

Where n is the number of individuals you want to simulate, and theta are: theta[1] = log(a) and theta[2] = b. You can fix theta[2] at some negative value.

   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 10, 2011, at 6:33 PM, Cliff Cunningham wrote:


	Dear Basta,

	I'm pleased to report that I have -- with an artificial dataset -- been able to recover patterns of declining mortality.  Thanks very much for fixing this!

	Is it possible to enforce declining mortality on a simulation (enforcing negative b1)?  I'd like to see how this affects the pattern of deaths in the life tables, as there are entire years with no deaths.
	
	
	Thanks very much!

	    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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