@TexasDemography
Basic Demographic Measures
Population Growth Forum
Region 10 Service Center
Dallas, Texas
July 14, 2016
Ninth
Eighth
Seventh
Sixth
Fifth
Fourth
Third
Second
First Billion
Number of years to add each billion (year)
All of Human History (1800)
130 (1930)
30 (1960)
15 (1975)
12 (1987)
12 (1999)
14 (2013)
14 (2027)
21 (2048)
Sources: First and second billion: Population Reference Bureau. Third through ninth billion: United Nations, World
Population Prospects: The 2004 Revision (medium scenario), 2005.
World Population Growth, in Billions
Billions
0
1
2
3
4
5
6
7
8
9
10
1950 1970 1990 2010 2030 2050
Less Developed Regions
More Developed Regions
Source: United Nations, World Population Prospects: The 2004 Revision (medium scenario), 2005.
Growth in More, Less Developed Countries
Population Increase and Growth Rate, Five-Year Periods
80
8783
7976 76 75
72
0
10
20
30
40
50
60
70
80
90
1980-
1985
1985-
1990
1990-
1995
1995-
2000
2000-
2005
2005-
2010
2010-
2015
2015-
2020
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
Net population added per year Annual population growth rate
Mill
ion
s
Pe
rce
nt in
cre
ase
pe
r ye
ar
Source: United Nations, World Population Prospects: The 2004 Revision (medium scenario), 2005.
Trends in Population Growth Worldwide
Thomas Malthus
Essay on the Principle of Population
• Relationship between population and
resources
• Population growth threatened prosperity
because it inevitably outran increases in food
supplies
• agricultural production grew
arithmetically, increasing by the same
amount over 25 years
• population grew geometrically, doubling
every 25 years
Population Clock
Modeling population and its consequences
Some models show population growth leading to resource depletion, which can result in declining food production, industrial output, and population.
Increasing our carrying capacity
Technology has allowed us to raise Earth’s carrying capacity for our species time and again.
Tool-making, agriculture, and industrialization each enabled humans to sustain greater populations.
Arithmetic Growth
population increases by a constant number of
persons for each period
arithmetic growth entails constant increments
Geometric Growth
Geometric growth entails ever larger increments.
Population increments become larger because increases are self-reinforcing
“compound interest”
Exponential Growth
Exponential growth refers to the situation where growth
compounds continuously - at every instant of time.
Annual Growth Rates
Logistic growth
“universal law of population growth”
S-shaped trend is a more realistic depiction of long-run national or
global population growth than straight lines or exponential curves
y = 406819e0.2695x
0
5,000,000
10,000,000
15,000,000
20,000,000
25,000,000
30,000,000
35,000,000
40,000,000
45,000,000
50,000,000
1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010
Population Expon. (Population)
Extrapolation of Texas Population Using Historical Data (1850-1990) -Exponential
0
5,000,000
10,000,000
15,000,000
20,000,000
25,000,000
30,000,000
35,000,000
40,000,000
45,000,000
50,000,000
1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010
Population Log. (Population)
Extrapolation of Texas Population Using Historical Data (1850-1990) - Logistic
y = 1E+06x - 3E+06
0
10,000,000
20,000,000
30,000,000
40,000,000
50,000,000
60,000,000
1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010
Population Linear (Population)
Extrapolation of Texas Population Using Historical Data (1850-1990) - Linear
Extrapolation of Texas Population Using Historical Data (1850-1990) -Polynomial
y = -54.89x5 + 3104.9x4 - 54032x3 + 422923x2 - 795476x + 708676
0
10,000,000
20,000,000
30,000,000
40,000,000
50,000,000
60,000,000
1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010
Population Poly. (Population)
Extrapolation of Texas Population Using Historical Data (1850-1990) -Polynomial
y = -54.89x5 + 3104.9x4 - 54032x3 + 422923x2 - 795476x + 708676
0
10,000,000
20,000,000
30,000,000
40,000,000
50,000,000
60,000,000
Population Poly. (Population)
Analyzing Growth
• Absolute change
• Percent change
• Average annual increase
• Arithmetic growth rate
Geometric Growth
• Estimating intercensal numbers, or projecting future population, assuming that the growth rate remains constant (growth rates usually vary through time)
Geometric Growth
Growth and Replacement
Age structure: Age pyramids
Canada (left) has a much slower growing population than does Madagascar (right).
Age structure: “Graying populations”
Demographers project that China’s population will become older over the next two decades.
Factors affecting population growth rates
Population growth depends on rates of birth, death, immigration, and emigration.
(birth rate + immigration rate)
– (death rate + emigration rate)
= population growth rate
Natural rate of population change
Change due to birth and death rates alone, excluding migration
Is often expressed in % per year
China’s natural rate of change has fallen
China’s rate has fallen with fertility rates. It now takes the population 4 times as long to double as it did 25 years ago.
Global growth rates have fallen
The annual growth rate of the world population has declined since the 1960s.
(But the population size is still rising)
Fertility rates affect population growth rates
Total fertility rate (TFR) = average number of children born per woman during her lifetime
Replacement fertility = the TFR that keeps population size stable
For humans, replacement fertility is about 2.1.
Total fertility rates by region
African nations have the highest TFRs.
European nations have the lowest TFRs.
INTERPOLATION OF POINT DATA
• Interpolation - inferring intermediate values in a given series of data by use of a mathematical formula or a graphic procedure.
• Extrapolation - inferring values that go beyond the given series of data by use of a mathematical formula or a graphic procedure.
Summary measures
• Sex ratios
• Dependency ratio
• Child dependency ratio
• Aged dependency ratio
• Economic dependency ratio
• Aging index
• Caretaker ratio
Central age – single year digits
• Mean - sum of values
number of values
• Mode - most frequently occurring value or group
• Median -middle value in a set of numbers arranged in ascending or descending order
Median age
• The median is preferred to the mean because of the marked skewness of the age distribution
• The calculation of mean is often complicated by open-ended age groups (e.g. 80+)
Age pyramids
• Gives a detailed picture of the age-sex structure of a population
• Consists of bars representing age groups in ascending order from lowest to highest pyramided on one another
• Bars are generally by single or 5-year age groups• Number (or percentage) of persons in an age group is
indicated by length of its bar from central axis• Males on left side; females on right side• Pyramids with absolute numbers show differences in overall
sizes of total populations and in number at each age• Percent pyramids show relative differences in population
size at each age-sex group
Age structure of Finnish population in 1917 and 2006
http://www.stat.fi/tup/suomi90/joulukuu_en.html
Texas Population Pyramid by Race/Ethnicity, 2010
200,000 150,000 100,000 50,000 0 50,000 100,000 150,000 200,000
Under 1 year
5 years
10 years
15 years
20 years
25 years
30 years
35 years
40 years
45 years
50 years
55 years
60 years
65 years
70 years
75 years
80 years
85 years
90 years
95 years
100 to 104 years
NH White Male Hispanic Male NH Black Male NH Asian Male NH Other Male
NH White Female Hispanic Female NH Black Female NH Asian Female NH Other Female
Source: U.S. Census Bureau 2010 Decennial Census, SF1
Texas non-Hispanic White and Hispanic Populations by Age, 2010
0
50000
100000
150000
200000
250000
Un
der
1 y
ear
4 y
ears
8 y
ears
12
yea
rs
16
yea
rs
20
yea
rs
24
yea
rs
28
yea
rs
32
yea
rs
36
yea
rs
40
yea
rs
44
yea
rs
48
yea
rs
52
yea
rs
56
yea
rs
60
yea
rs
64
yea
rs
68
yea
rs
72
yea
rs
76
yea
rs
80
yea
rs
84
yea
rs
88
yea
rs
92
yea
rs
96
yea
rs
10
0 t
o 1
04
…
Po
pu
lati
on
Age
White (non-Hispanic)
Hispanic
Source: U.S. Census Bureau 2010 Decennial Census, SF1
Contact
Office: (210) 458-6530
Email: [email protected]
Internet: demographics.texas.gov
Lloyd Potter, Ph.D.
@TexasDemography