SOCI 358 - Population Challenges of the 21 st Century Notes WEEK 1: 2. Some basic notions in Demography Demography refers to the scientific study of human populations, with respect to their size, distribution, structure and development (dynamics, processes: mortality, fertility and nuptiality, migration). I use the Canadian population to illustrate some of these notions, as per the text in reference for this week: Martel Laurent, "Recent changes in demographic trends in Canada", Insights on Canadian Society, Statistics Canada, Catalogue no. 75-006-X, October 2015, 10 pages. In this text, Martel describes the components of growth for Canada as well as the provinces and territories (birth rate, death rate, and net migration rate). He also examines their impact on various characteristics of the population (its structure): age, birthplace visible minority status, and regional distribution in Canada. Population Growth *According to the population numbers published yearly by Statistics Canada (Annual Demographic Estimates) the size of the Canadian population in 2011 and 2014 was, respectively, 34,482,800 and 35,540,400. Using these numbers in the formula for the percentage of growth, you get a percentage of growth of 1.03%. - Take the time to understand how this bar graph is organized: horizontal axis (each province or territory) and vertical axis (percentage of growth) - Percentage of growth a little above 1% for Canada: ((P2014-P2011) / P2011) x 100* - Variations within Canada: largest and lowest values? What could be the reasons for that? Note that the growth is slightly negative in one province, Nova Scotia (decline instead of a population increase).
- Difficult to discuss the reasons for such differences without looking more closely at the components of growth. Is the growth in Alberta mostly due to migration or to a high birth rate? What is going on in Nova Scotia or New Brunswick to explain such low growth rates? The Components of Growth - Births and immigrations contribute to increasing the population while deaths and emigrations make it decline. The population growth will be positive if the number of births and entries, combined, surpasses the number of deaths and departures, combined. - Natural increase = Number of births - the number of deaths. When divided by the population and multiplied by 100 (or 1,000), these quantities can be referred to as birth rate, death rate, and rate of natural increase. - The same reasoning applies to the migration component. The net migration rate = the difference between the immigration rate and the emigration rate. - At the provincial level, one additional component must be considered: the interprovincial migration rate and whether a province or territory gained more people from other provinces than it lost to them. - Knowing this, what does this graph tell us to help understand the various growth rates observed in Chart 1 (represented in red on Chart 2)? Why was the demographic growth rate so low in Nova Scotia in 2014 and why was it so high in Alberta? Population Development (Growth) Population Structure - Each bar on this graph represents the distribution of the population in each province or territory according to birthplace, in 2011. Individuals were born either in the same province or territory, outside of Canada, or in another province of territory.
- Although we do not have a full account of past net international migration rates in this article, it is quite clear from this graph that provinces such as Ontario and British Columbia that are/have been important destinations for immigrants have larger shares of their population born outside of Canada. On the other hand, a large percentage of the populations in the three territories was born in other provinces (workers most likely attracted to these places). - Migration rates - › Birthplace composition The Structure of the Population also Impacts the Population Growth - In fact, there is a bidirectional relationship between these two domains of interest in Demography, the population structure and its development (or growth): population development + > population structure - An example of how the population structure may influence the growth is when a population is getting older, and its birth rate declines due to a declining proportion of women (and men) in their reproductive ages - Laurent Martel does allude to this in the following excerpt: "This article has shown that current population growth trends, the factors underlying this growth, and the age structure should continue to contribute to the growing demographic differences from one region of the country to another ." p.8. Two additional remarks about the graphs we examined 1) Where does the data come from? Pay attention to the Sources mentioned at the bottom of tables and graphs, and the section where the authors present the data sources and methods they used in their analysis. Typically, the census is a very important source of information about the structure of the population. The 2011 National Household Survey mentioned at the bottom of Chart 5 corresponds to the 2011 Census which had been transformed into a survey by the Harper government, against experts' recommendations. It was switched back to the compulsory census format in 2015 by the Trudeau government. Typically, measuring population growth requires the continuous registration of births and deaths (in what is called Vital Statistics ) and of entries/departures over a certain period (Immigration statistics - There is no systematic registration of departures in Canada).These sources were used to produce the population estimates referred to at the bottom of Charts 1 & 2.
Surveys are another very important source to study demographic issues. They yield representative information about both population characteristics and components of growth such as fertility trends and determinants. We will encounter other complementary sources in the readings to come and will pay attention to them in each specific context. 2) Demographic facts/analyses do not, exist in a social vacuum To understand the demographic trends - basically how a population gets reproduced one must refer to the society in which these trends are observed. For example, the economic situation of a province is closely related to the migration rates, both international and interprovincial, observed in this province. The cultural specificity of the Quebec province is most likely associated with lower interprovincial migratory rates usually observed in this province. Similarly, demographic trends and changes have consequences for the society in which they occur. The aging of the population, a consequence of both lower birth rates and declining death rates, poses some challenges to our societies in terms of labour force management and pension costs, for example. Chart 9 in the article by Martel invites us to think about a variety of consequences that differential demographic growth rates for various provinces and territories might have in Canada. Consequences of Differential Population Growth in Canada - Note that Chart 9, a clustered bar graph, is based on both observed and projected regional distributions of the Canadian population (more to come about population projections in next classes). - Take some time to figure out how the distributions provided on this graph add up to 100%. (Hint: imagine what the table behind this graph would look like) Add all columns that have same colour in order to get up to 100% EX: Atlantic (21) + Quebec (32) ...+ (...) in 1871...add all column regions in 1871, then 1961, so on (...). - Identify the long-term trends apparent on this graph and think about some historical causes that might be responsible for them.
- What about the consequences: social, economic, cultural, political? Demographic Regimes in Transition 2.1 Demographic transitions In Demography, the term "demographic transitions" refers to important shifts that occurred in the way populations get reproduced. 1. The first demographic transition (FDT) refers to the transition from a demographic regime where birth rates and death rates were high to a situation where both rates declined to a much lower level. It took place roughly between 1850 and 1950 in what we now refer to as high- income countries. It also took place soon after in most other countries, some of which still experience relatively high birth rates and death rates today. * A demographic regime designs the various conditions under which populations get reproduced: the combination of the age at the formation of unions, whether people use, or not, contraception, the risk of dying at various ages, the likelihood that people will emigrate, fertility rates at various ages... that will yield a given reproductive outcome for a population. 2. The second demographic transition (SDT) refers to major transformations that have affected marriage and the family, including fertility rates, mostly in high and medium- income countries since 1970. These transformations point to less stable unions (cohabitation and divorce), the growing diversity of family forms, and sub- replacement fertility that is often postponed at later ages. A Representation of the First Demographic Transition In most cases, the mortality decline preceded the fertility decline.
The significant impact of the first demographic transition on the world population growth. Different patterns of the first demographic transition
According to the 2020 World Population Data Sheet, the birth rate in the least developed countries, combined, was 33‰ and the death rate 7‰ Important differences in the features of the first demographic transition in various contexts Summary of differences 1. The pace and sources of the mortality decline 2. The fertility levels before the decline 3. The rate of population growth 4. The momentum for further growth 5. International migration during the transition Evidence of the first demographic transition in Canada: increase in life expectancy, declining fertility rates The life Year Life expectancy at birth (in years) Total fertility rate ~ 1870 45-50 % of change 7.0 % of change 1921 57.0 +21% 3.3 -53% 1981 75.5 +32% 1.7 -48% 2011 81.7 +8% 1.6 -6%
expectancy at birth is the number of years one can expect to live under the mortality conditions of a particular year. Its increase reflects the decline of mortality. The total fertility rate is the number of children a woman can expect to have during her reproductive life under the fertility conditions of a particular year 2.2 The mortality declines during the first demographic transition and beyond The mortality transition, also referred to as the epidemiological transition, was characterized by a significant decline in mortality levels, and a shift in causes of death from infectious to degenerative diseases. According to Bourbeau and Ouellette, children, youth and women benefitted more from the decline at the beginning, partly because they were more affected by infectious diseases and partly because risk factors such as smoking played a less important role for women. What prompted the mortality decline? 1. Public health and sanitation measures Since the last decades of the 19 th century. Examples: sewage system, water chlorination, milk pasteurization, less crowded dwellings... 2. Improved living conditions and socioeconomic status Since the last decades of the 19 th century. Any exception to this? 3. Development of medical knowledge Examples: Vaccination (as early as the 1880s); antibiotics (1940s); cardiovascular therapy (1970-80) and preventive approach to remaining healthy (more recent) 4. Better access to health services From clinics for pregnant women and their children to the implementation of a universal health care system. What future for our health system? 5. Improved lifestyle Since the 1990s especially. Oriented towards a reduction of man-made diseases: physical exercise, no smoking, eat healthy, fasten your seat belt ... Brief overview of mortality indicators to account for mortality trends Crude death rate
Number of deaths (period) X 1000 Population o The numerator in that formula comes from Vital statistics (death certificates) while the denominator comes from censuses (or population estimates between censuses) o See the range of values from previous graphs of the FDT (slide 7) Crude death rates are too crude to account for the fact that the risk of dying varies according to age (it is much higher at older ages) and older populations may thus be affected by higher crude death rates simply because they are older (and not because the risk of dying is in fact higher) We use Age-specific death rates to overcome this limitation and establish a more appropriate basis for comparison. Same formula as before but for specific age groups. o Example of the computation of death rate at ages 55-59: Number of deaths from people aged 55-59 X 1000 Population aged 55-59 One special type of age-specific death rate: the infant mortality rate, a very powerful indicator (see slide 13) Definition: Number of deaths from children under one year of age X 1000 Total number of births during the same period Using age-specific mortality rates transformed into probabilities of dying at each age, one can compute Life tables, a more sophisticated tool to describe mortality trends (slide 14). The content of the life table can be summarized by measures of central tendency such as the life expectancy at birth (e0), which is the mean length of life for a group of people experiencing the risks of dying of that life table. Not all age groups benefitted from the decline at the same pace (slide 15). Life expectancy can also be computed at any other age: e1, e65, etc... (slide 16) The spectacular decline of infant mortality rates in Canada: What a life table looks like (excerpt only):
Table 1c. Complete life tables, both sexes, Canada 2017 to 2019 Meaning of headings: l x = number of survivors at age x d x = number of deaths at age x q x = probability of dying at age x e x = life expectancy at age x Larger gains for children followed by larger gains for young and older adults
Sex differentials in mortality: trends at various ages and main explanations Why do men experience higher mortality than women? Three main categories of explanations: 1) Biology/genetics 2) Risky behaviour 3) Preventive approach to health How do we explain the narrowing gap between life expectancies for men and women? Other changes: death is becoming a more homogeneous event in terms of age Measuring the shift in the main causes of death To assess mortality by cause 1) Death rates for specific causes of death: the number of deaths (numerator) only includes the deaths from a particular cause or set of causes, e.g. heart diseases o The classification of causes is the one from the World Health Organization. Subject to constant revisions. 2) Overall distribution of deaths by causes o Table 1 in the text by Bourbeau and Ouellette contain both indicators. The death rates are provided per 10,000 population (change of scale because the rates are smaller). o The notion of life expectancy can be further qualified: life expectancy in good health (Healthy Adjusted Life Expectancy). Health surveys are useful to compute such indicators.
Declining death rates for most causes of death: 2.3 The fertility declines during the first fertility transition and beyond What the fertility decline looked like in Canada Year Life expectancy at birth (in years) Total fertility rate ~ 1870 45-50 % of change 7.0 % of change 1921 57.0 +21% 3.3 -53% 1981 75.5 +32% 1.7 -48% 2011 81.7 +8% 1.6 -6% The total fertility rate is the number of children a woman can expect to have during her reproductive life under the fertility conditions of a particular year. It is a period measure. Pay attention to the fact that a significant fertility decline occurred prior to 1921, that is well before the introduction of
modern contraceptives such as the pill. Along with the decline, the mean age of women at childbearing declined as well; then it went up again with the postponement of fertility during the second demographic transition (slide 21) What prompted the fertility decline? Theoretical explanations in context. Period Fertility trends Theoretical explanations 1850 → 1940 Fertility transition in developed countries The demographic transition theory (1930s- 1950s) makes room for demographic, economic and cultural explanations of the fertility decline 1940s - 1960s ▪ Baby boom in developed countries ▪ Mortality decline in developing countries NOT followed by the expected fertility decline The Demographic Transition Theory is challenged 1970s - 1980s Fertility transition in some developing countries (Asia, South America) ▪ Much emphasis put on cultural factors (Princeton project on European fertility decline & World Fertility Surveys in developing countries) ▪ Caldwell's wealth flow theory 1990s → ▪ Many developing countries experience fertility transitions ▪ Fertility fluctuations below the replacement level in Women's role; more focus on detailed local studies and agency Integration of cultural and economic approaches rather than opposition
developed countries A chronology of explanations The demographic transition theory (1920-1960) The mortality decline Adaptation to new socio-economic conditions: no need to have as many children as before, new aspirations, prolonged and compulsory schooling, ... Micro-economics approaches: substituting quality to children quantity (Becker) Cultural explanations and the diffusion of new ideas and new norms. Lessons from the European fertility project and surveys in developing countries (1970- 1980) Caldwell's theory of inter-generational wealth flows (1980): the inversion of wealth flows from children (economic asset) → parents within the family to parents → children (more of an economic burden) is key to understanding the fertility transition. Feminist approach and women's empowerment (1990 onward) Some characteristics of these explanations: Cultural versus economic explanations applied to the context of developing countries leads to the Population ↔ Development debate. Micro-macro explanations Fertility transitions at the world level Total fertility rates in various regions of the world, 1960 and 2020 Population challenges associated with long-term demographic transitions: how we see them
CLASS 2: WEEK 2 Demographic Regimes in Transition: The demographic equation is a mathematical expression which represents the population dynamics during a certain period P (t+1)= P (t) + B (t, t+1) - D (t,t+1) + | (t, t+1) - E (t,t+1) The difference between the number of births (B) and deaths (D) is called natural increase. The difference between the number of immigrants (I) and emigrants (E) is called net migration. The combination of natural increase and net migration is responsible for the population growth, either positive or negative. Example for Canada, in 2012 (NPR stands for non-permanent residents): P 2013-01-01 - P 2012-0-1-01 +B 2012 - D 2012 + I 2012 - E 2012 (+ NPR) 35,056.064=34,671,306 + 384,549 - 256.965 + 257.730- 47.528 (+46,972) A rate is defined as the number of occurrences for a given phenomenon, divided by the population where the phenomenon occurs, during a given period: N of occurrences x 100 Population Following this definition, the crude death rate (CDR) is defined as Number of deaths (period) x 1000 Population (mid-period) and the crude birth rate (CBR) as Number of births (period) x 1000 Population (mid-period) Population (mid-period) = (34,671,306 + 35,056,064) / 2 = 34,863,685 Similarly, the rate of natural increase is defined as the difference between the two rates above: RNI = CBR - CDR Demographic rates for Canada in 2012:
CBR = 11.0%, CDR = 7.4%, RNI = 3.6% (or 0.36%) Other basic rates: - Rate of immigration (7.4 %0) - Rate of emigration (1.4%o) - The net migration rate (6.0%o) - The population growth rate is the sum of the rate of natural increase and the net migration rate (9.6%o or 0.96%). It can also be computed as P(+1) - Pt x 100 P(mid-year)
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