1
Population and Migration Studies: Worksheet 1
Continent
Africa
Asia
Europe
Latin America
North America
Oceania
World Total
total (millions)
% world
pop./sq. mile
100%
Country
millions
% of world total
1
2
3
4
5
6
7
8
9
10
*Check out the data for yourself at www.prb.org
There are three fundamental mechanisms which influence populations and their structure: births,
deaths and migrations.
The purpose of this worksheet is to introduce some of the basic
calculations which are used to understand the nature of populations. Typically, demographic
variables are expressed as rates. A rate is a measure that reflects the frequency of an event
(such as birth), relative to the population that may experience that event.
Rates are useful
because they allow us to make comparisons between different populations and because they can
be compared across time to discover trends in a particular population.
Measuring Fertility: CRUDE BIRTH RATE
The crude birth rate (often referred to simply as the birth rate) is the most commonly used index
of fertility. This is the ratio of the number of live births each year to the total population (usually
measured at the mid-point of the year).
It is expressed as the number of births per 1,000
population. e.g. if 3,000 babies were born in a population of 150,000, then the crude birth rate
would be 20 per 1,000.
1. Why is it called a crude rate?
Population and Migration Studies, 2004-2005
©Dr Ruth McManus, 2004
2
Measuring Mortality: CRUDE DEATH RATE
The crude death rate is the number of deaths per 1,000 members of a given population. It may
be calculated for the population at the mid-point of the year or at the beginning of the year.
2. What are the disadvantages of using crude rates to measure mortality and fertility?
Population Growth: NATURAL INCREASE
Natural increase is a simple measure of population growth which examines the differences
between births (fertility) and deaths (mortality) in a given group. It is usually determined by
subtracting the crude death rate from the crude birth rate. Natural increase is generally expressed
as a percentage figure. e.g. an annual natural increase of 0.8 means that a country is increasing
its population by 0.8 per cent each year.
If the death rate is greater than the birth rate, then a population may be experiencing natural
decrease.
3. What aspect of population growth or decline is not measured by the natural increase
calculation?
Births and Deaths in the Republic of Ireland, 1995 – 2002 (selected years)
Source: CSO, 2004
1995
1998
2000
2002
Births
48,787
53,600
54,239
60,521
Deaths
32,259
31,400
31,115
29,348
3,601,300
3,704,900
3,786,900
3,917,203
Total Population (estimated)
4. Calculate the Birth and Death Rates for Ireland in each of the four years
5. Calculate the Natural Increase for Ireland in each of the four years.
6. Write a short paragraph outlining the population changes experienced over the period
from 1995 to 2002, based on this data.
The main source of population data for the Republic of Ireland is the Central Statistics Office:
www.cso.ie. Visit the CSO website and find the following information. You may have to dig deep,
but most answers will be either in Demography and Labour Force or the Vital Statistics section.
8. What was the population of Ireland in 1901?
9. How many Irish speakers aged 3 years and over were enumerated in Connacht in 1961?
10. In which census year of the 20th century was the lowest total population recorded in
Ireland?
*What is the most important point to remember from today’s lecture?
Population and Migration Studies, 2004-2005
©Dr Ruth McManus, 2004