Generation Length T Intrinsic Calculator
Compute the intrinsic mean generation length T either as ln(NRR)/r from Lotka's relation or directly as the mean age of mothers at childbirth of the net maternity schedule.
Description
Compute the intrinsic mean generation length T either as ln(NRR)/r from Lotka's relation or directly as the mean age of mothers at childbirth of the net maternity schedule.
Compute the intrinsic mean generation length T either as ln(NRR)/r from Lotka's relation or directly as the mean age of mothers at childbirth of the net maternity schedule.1
When to use Generation Length T Intrinsic Calculator
Use this stable-population relationship for analytical schedules whose fertility, mortality, migration assumptions, and age intervals match the model.
- Method
- Formula choice: Lotka's ln(NRR)/r or the mean age of maternity.
- NRR
- Net reproduction rate NRR (Lotka method).
- Growth rate r
- Intrinsic annual growth rate r (Lotka method).
- ASFR
- Fertility rates per woman per year (mean-age method).
- L(x)
- Life-table person-years L(x) aligned with the rates (mean-age method).
- Start age
- Starting age of the first class in years.
- Class width
- Width of each age class in years.
How the method works
- T
- Mean generation length in years.
Limitations and assumptions
Stable-population identities assume fixed vital rates and usually a closed population. Real populations with changing schedules or migration may be far from the implied equilibrium.
Alternative or Complementary measures
Compare the stable-population result with an observed age distribution or a cohort-component model using changing schedules. The difference indicates how strongly the equilibrium assumption shapes the result.
References
-
Euler–Lotka equation — Wikipedia contributors
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