Age-Sex Pyramids Flashcards
(25 cards)
age at last birthday vs exact age
age at last birthday is simply your current age (determined once your birthday hits)
exact age is the years and # of months / 12
age heaping
when respondents round up or down their age … can be caused by cultural preferences or misreporting
what’s a male dominated sex ratio? if I gave you a sex ratio of 101.1, would that mean there’s more/less men than women
anything over 100 means there’s more males than females
… recall that the formula is males/females * 100
if fertility is increasing, is the population getting older or younger
younger, always
what is the longest and greatest affect on population age structure: fertility or mortality?
fertility … mortality has a more ambiguous effect
if a country’s mortality were to decrease from moderate to low, would the population become older or younger
in countries with low mortality, these deaths are usually occurring at older age levels … so the population would become older, as the elderly stick around longer
if a country’s mortality were to decrease from high to medium, would the population become older or younger
in countries with high to moderate mortality, these deaths are typically occurring at infant ages … so the less they die, the younger the population becomes
if a country’s mortality rate were to increase from low to moderate, would the population become older or younger
if the country has low mortality right now, it is likely centered around elderly people dying … so increasing this to moderate would take out more old people, making it a younger population
if a country’s mortality were to increase from moderate to high, would the population become older or younger
this is extremely rare in contemporary societies, so we don’t have a concrete answer (infant mortality will likely never rise to their historical levels)
what are the five pyramid types in population studies
expansive (I), expansive (II), bell shape, stationary, and constrictive
explain the shape of the five pyramid types
expansive (I): big teepee, triangle
expansive (II): small teepee, triangle
bell shape: rounder bottom than expansive II, less of a triangle
stationary: beehive/barrel shape … rectangular with equal-ish weights between 0 - 55
constrictive: smaller bottom than middle and top
which pyramid most closely relates to the 5th stage of the demographic transition?
constrictive, where there’s very low fertility and mortality (but fertility is lower than mortality)
population is ageing, with high dependency ratio
Japan in 2025
describe expansive I to the viewers
high fertility and mortality … w high population growth
very wide base and very narrow top, looks like a big teepee
developing countries (Niger) have this
describe expansive II to the viewers
high fertility and rapidly declining mortality … still high population growth
more of an equilateral triangle
better developing countries have this (Ethiopia)
describe bell shape to the viewers
falling fertility and mortality now … population growth falls but pop. size still grows
shaped like a rounder triangle … not as wide of a base anymore, narrowing at the bottom
World in 2025 looks like this
describe stationary to the viewers
low fertility and mortality, population growth has stabilized … slow growth
rectangular appearance, similar %s from 60sdescribe expansive I to the viewers to bottom
describe constrictive to the viewers
very low fertility and mortality, with fertility being lower than mortality … very low or negative pop. growth
narrower bottom than the rest of pyramid, wider share towards the top
Japan has this in 2025
explain replacement level fertility
the fertility rate needed to exactly replace parents and maintain constant population
typically 2.1 for developed countries; two kids to replace parents; this figure is ~2.3 in developing countries
if total fertility rate < replacement level, then will population grow or decline
it will decline, given that replacement level is the rate needed to keep population size flat
explain population momentum and how a bigger/smaller birth cohort affects future cohorts
the relative trend of cohort sizes indicates population momentum … if cohorts are getting larger, then subsequent cohorts will also be larger
… conversely, if cohorts are becoming smaller, then future birth cohorts will become smaller
what is the key assumption when discussing population momentum?
mortality conditions remain constant … i.e. if TFR fell to replacement level, then all else equal you would see a stationary pyramid after 70 yrs
this is because the birth cohorts above it would stay alive while future cohorts would match the size of the ones above it
explain positive population momentum and why fertility rates tend to be a lagging indicator of population growth
positive population growth is where the pop. growth rate falls until it hits the replacement level
i.e. a rapid growth population will eventually stabilize at replacement level … can’t maintain it in perpetuity
BUT even once you hit replacement level, the birth cohorts were successively larger than those before them (from the rapid growth)
So, even at replacement level fertility, they’re going to produce future cohorts that are larger than those before them (since there’s more people producing at replacement level)
conversely, describe how negative population momentum works
this is where a low/negative population growth country eventually reaches replacement level fertility
… BUT since these cohorts before them were successively smaller than those before them … they will produce smaller cohorts as there’s less people producing
describe the demographic dividend to the audience
high working age pop. (15-49) and low dependents
time-limited period for a country to benefit from outsized growth in capital stock (higher savings & investment) from working age ppl
requires high fertility, then low fertility to build up the population and then capitalize on it … no babies allows more money to enter economy (more disposable income)
