population transition matrix

[Camilla Stefanini]

Hi all, 

I have a doubt on how to build my transition matrix. I have a population of trees and the age structure is 0 (seedlings), 5 (young trees), and adult age classes 30,50,70,90. 

I want to set the matrix in a way that for the adult classes, the P surviving is 0.98 and at the end of the stage they all transition to the next stage. 

My doubt is, how should I set the P survival (on the diagonal) and the P transition?

The individuals stay in adult stages for 20 years, before reaching the transition age.  

If I understood well, the total P for each stage should be Psurvival + Ptransition  = 0.98, 

but If I set  Psurvival = 0.98 (so that almost all survive before reaching the transition age), I cannot set P transition = 1, but If I set P transition = 1 I cannot set P survival = 0.98, which means they will die the years before reaching the transition stage. 

I think I have missed some basic point, I could not find this answer in the manual and in the examples. Below my script, to make the problem clearer. 

thanks for any input!

Camilla 

[Olivier Cotto]

Hi Camilla,

You should be perform what you describe by using "pop_transition_by_age" (see manual) :  if you set s_ii = 0 and t_ij = 0.98, the function works such that p(surv) = 0.98 when age < age_max and p(surv)*p(transit)=0.98 when age = age_max (i.e. p(transit) = 1). [Thanks Fred for the input!]

I hope that this will help, and let us know if this solution does not work.

Cheers,

Olivier

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