gen.time {demogR} | R Documentation |
Calculates the generation time for an age or stage-classified demographic projection matrix.
gen.time(A, peryear = 5)
A |
demographic projection matrix |
peryear |
width of the age classes |
Calculates the generation time (T) for an age or stage-classified demographic projection matrix using the identity
$R_0 = \exp(r*T)$
where $R_0$ is the net reproduction number and r is the intrinsic rate of increase (=log(lambda)).
Generation time is the amount of time that it takes a typical female to produce $R_0$ offspring or, equivalently, the amount of time it takes a population growing with instantaneous rate r to increase by a factor of $R_0$.
The generation time implied by the demographic projection matrix.
Calls function calc.ro
, which calculates $R_0$ from the
fundamental matrix of the Markov transition matrix (Caswell 2001).
Keyfitz, N., and H. Caswell. 2005. Applied mathematical demography. 3rd ed. New York: Springer.
Caswell, H. 2001. Matrix population models: Construction, analysis, and interpretation. 2nd ed. Sunderland, MA: Sinauer.
Preston, S.H., P. Heuveline, and F. Guillot. 2001. Demography: Measuring and modeling population processes. Oxford: Blackwell.
## compare generation times from two populations with very different ## R_0 values data(goodman) ven <- with(goodman, life.table(x=age, nKx=ven.nKx, nDx=ven.nDx)) ven.mx <- with(goodman, ven.bx/ven.nKx) A <- leslie.matrix(lx=ven$nLx,mx=ven.mx) usa <- with(goodman, life.table(x=age, nKx=usa.nKx, nDx=usa.nDx)) usa.mx <- with(goodman, usa.bx/usa.nKx) B <- leslie.matrix(lx=usa$nLx,mx=usa.mx) gen.time(A) gen.time(B)