L5-6 Demography

Question 1

what is the age/sex structure of populations determined by

Answer 1

birth and death rates

Question 2

what does an ageing population indicate

Answer 2

• Increased survival and decreased birth rates

* As populations age they also feminize (greater proportion women)

Question 3

how do populations respond to resource/population dilemma

Answer 3

o increase in mortality (catastrophic, vices i.e. war, famine), or
o decrease in fertility (not enough resources, virtues)

Question 4

what are the independent interval elements of life tables

Answer 4

• nx
• dx
• qx
• fx

Question 5

what is nx

Answer 5

Independent 
•	nx = Number entering an age class observed in a cohort LT, constructed in a synthetic LT 
o	E.g. if x=0, how many births 
o	X=1, howmany enter at age 1, how many are one

Question 6

what is dx

Answer 6

independent

number who die during that period

Question 7

what is qx

Answer 7

Age specific mortality = dx / nx

o = Number die in interval / number entering interval

Question 8

what is fx

Answer 8

probability of woman giving birth during interval x

Question 9

what are the cumulative interval elements of life tables

Answer 9

LX
Lex
TFR

Question 10

what is lx

Answer 10

= probability of surviving to age x from birth = nx / n0 (if no emigrations) Each age interval is not independent
o L7 = prob to reach age 7 from birth (not during one interval or one year)
• Doesn’t show mechanisms, i.e. do neonates die or 6 yr olds die
o Must use different equation when indivs appear or disappear

Question 11

what is lex

Answer 11

expected (=average) additional years to live at age x = “life expectancy” (each point reflects average future survival)
o Sum of death rates, given death profile of pop,
• When you’re born expect to live x years, but when your x years old expect to live x more years
• Life expectancy can increase
o Early death = approx 90 years NOT alive // more impact on life expectancy stats than later death who only loses 20 years to total (already contributed 70 years to numerator)
• Massive changes in historical = reduction of infant and child mortality NOT old people living longer

Question 12

what is TFR

Answer 12

(females only) = total fertility rate = sum of fx over xi to x50
o Prob of giving birth at each age (15>50), what the prob of giving birth at x=4, 0)
• Total fert= SUM of these points
o Allows compare of pop

Question 13

Define life expectancy at birth

Answer 13

‘Average number of years that a newborn is expected to

live if current mortality rates continue to apply.’ (WHO)

Question 14

difference between Surivorship (Lx accumulative) vs Mortality (Qx)

Answer 14

Lx: survival from birth (accumulative)

qx
• Each age gap is independent
• Differential/comparision

Question 15

why do males have higher survivorship (lx)

Answer 15

• Males tend to be higher survivorship
o Hyp: aspect of health that effects females disproportionally
o Hyp: Cultural favour of males
• Large death rate in first year

Question 16

what is the heterogametic sex disadvantage

Answer 16

Evidence of excess male mortality

Question 17

explain the male mortality shoulder

Answer 17

• When theres a Decrease in mortality= Female mortality decrease more consistency than males
• Access male mortality in early adulthood
• Hypothesis:
 Less risk averse males (cultural phenomena?)
 Males competition for mates // = seelction for more risk averse