← All parts of this equation

Equation 4 · Part 6 · Demography, Migration, and Urban Futures in Practice: An Advanced Technical Guide

multiplication

Pa+1,s,t+1=Pa,s,t⋅Sa,s,t+Ma,s,tP_{a+1,s,t+1} = P_{a,s,t} \cdot S_{a,s,t} + M_{a,s,t}
multiplication

What this part means

Multiply the quantities on either side.

Its job in the formula

Multiply the quantities on either side.

The passage around this formula

Aging the cohort forward. For each one-year (or five-year) step, every age-sex cohort is advanced by applying an age-specific survival ratio — the probability of surviving from one age to the next, derived from a life table built out of registered deaths and mortality schedules — and then subtracting deaths and adding net migrants assigned to that same age and sex [ 1 ] . Symbolically, for a cohort of age a and sex s in year t : Pa+1,s,t+1=Pa,s,t⋅Sa,s,t+Ma,s,tP_{a+1,s,t+1} = P_{a,s,t} \cdot S_{a,s,t} + M_{a,s,t}. where P is the population count, S is the age-and-sex-specific survival ratio for that interval, and M is net migration assigned to that cohort during the interval. The youngest cohort in each step is not aged forward from an existing cohort; it…

Read this part in the article →

Learn the underlying idea

Multiplication scales one quantity by another. A dot, a cross, or adjacent symbols can indicate a product.

Open the illustrated multiplication: combining factors guide →

Sources cited in the surrounding passage

These citations provide research context; check each source for the exact claim it supports.