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Introduction to Demography

July 17, 2017
by Russ Long



Population growth is most intense in the poorest nations of the world. World Watch (in World Development Forum, November 15, 1988) argues that some [population] increases projected for individual countries by World Bank Demographers are staggering. The population of Bangladesh, now 110 million, will triple before it stabilizes. Nigeria's population, now more than 100 million, is projected to reach 529 million before it stops growing late in the 21st century. The forty-three million people of Ethiopia, where a combination of soil erosion, ill-conceived agricultural policies and nonexistent family planning programs have already led to widespread starvation, are projected to quintuple in number. Even with heavy emigration, Mexico's current population of eighty-two million may more than double before stabilizing.

I.     What is Demography?

Demography is the study of population. It looks at everything that influences population size, distribution, processes, and the influence that change in population has on other contemporary issues. Major components of Demography include the following.

A.     A Demographic Perspective

The demographic perspective influences the way people understand and interpret questions involving population. Three are presented in this article (the Malthusian perspective, the Demographic Transition model, and the Marxist perspective).

B.     Population Processes

Three basic population processes include birth, death, and migration. Questions about population processes might include: Is the population becoming older or younger? Where do people live? Where are people migrating to and where do they come from?

C.     Population Structure

Population structure addresses the relationship between population processes and demographic characteristics of populations such as the age and sex of a given population, the race and ethnicity of a population, their socioeconomic status, and perhaps their marital status.

D.     Population and Contemporary Social Issues

Weeks (1989) explores the demographic underpinnings of several major issues confronting the world. Weeks (6:1989) contends population growth is often incendiary in that it "ignites" other social problems that people face. Demographic processes and structure interact with the following social issues: Food security, women's rights, family structure, unemployment, aging, housing and urbanization, economic development, inflation, energy, pollution and the ecosystem, literacy and education, and finally issues about individual freedom.

II.     Uses of Demography

Much sociology appears ethereal and difficult to grasp. Demography is one of the more pragmatic areas of Sociology (See Weeks, 1996:5).

A.     Demography and Business

Business can put the study of population to specific uses.  If, for example, a business sells a product that is desired by age-specific groups, that business can use the census to discover communities where members of that age-specific group live.  For example, a business may want to open an automobile dealership that specializes in expensive sports cars. Demographic awareness could help the potential dealer in finding neighborhoods where young and middle-aged affluent people live. Placing a Corvette shop in a working-class community populated mainly by low-income middle-aged and elderly people could be disastrous.

B.     Demography and Government

Demography is also an essential tool used in ensuring equal representation in Congress. Population distribution determines the makeup of the House of Representatives. As people move from one state to another, the makeup of the House of Representatives changes (See Weeks, 1996:10-11).  The last reapportionment occurred in 2000 at the Federal level. Sunbelt states gained seats in congress while Rust-belt states lost seats. Assuming the South continues to vote Republican, reapportionment could help the Republicans gain seats in the House of Representatives in the next decade.

C.     Allocation of Money for Social Services:

This point also pertains to the relationship between Demography and the Government (part B). Given that it is important for the allocation of money to poor people, one can understand why disadvantaged groups in society are at a farther disadvantage when the Census Bureau under counts those populations.

III.     The Baby Boom

A.     What is the Baby Boom?

The baby boom represents a demographic event that is well-documented and which has had, and which will continue to have, significant impact on American society (see Weeks, 1996:157-158). The baby boom began in the late 1940s and continued through the 1950s. Although it ended in the 1960s, the baby boom still influences the structure of the population as well as an array of social institutions. Furthermore, its effects will echo far into the future.

B.     What caused the baby boom?

The baby boom occurred because of three events.

1.     People postponed having children during the great depression. The depression was not a good time to have children given that more than 25 percent of the population was unemployed.

2.     Later, people were forced to postpone childbearing because of World War II. Many men were out of the country and the economy was still not conducive to encourage child birth.  At the end of the war, the men came home and the economy boomed. People who had postponed having children during the great depression and during the war decided it was a good time to have children.

3.     Further, given the robust state of the American economy, people who would normally have had children during the 1950s had more children than usual.

C.     The Impact of the Baby Boom on Social Structure

The impact of the baby boom was felt in all age-specific institutions in America.  Initially the increase in newborn babies swamped hospital maternity wards. Within five years of the beginning of the baby boom, schools became overcrowded with new children. The same thing happened to colleges and, finally, the job market. By the year 2010, Social Security could also be overwhelmed with the same surge of people that began moving through the population of our society in the late 1940s.

D.     A Baby Recession?

After the baby boom generation has passed a particular social institution specifically oriented toward age (like school), a recession of sorts occurs. Initially, organizations, like schools, had to catch up. The government undertook massive school building programs. The baby boom required the training of hundreds of new teachers on short notice. After the "baby boomers" had moved through their elementary school years, there were too many teachers and too many schools. (Note: the present teacher shortage is not related to the baby boom phenomenon.)

E.     Baby Boomlets and Echo Effects

Furthermore, baby boomlets (also called "echo effects") can be expected for the next few generations to come (weeks, 1996:1580159). The effects of the baby boomlets will not be as dramatic as the "big boom," but will cause headaches for urban planners as they try to cope with a fluctuating population. Dramatic changes in population structure can influence the economy and the environment as well. Changes in the population can create new markets. It can affect pollution, housing, energy availability, living space, and ultimately freedom.

IV.     Three Demographic Variables

QUESTION: How does population change?

The population changes in accordance with three demographic variables:  Fertility, mortality, and migration.  Population growth or decline in a society is influenced by the birth rate, the death rate, and the migration rate.

Crude Birth Rate

The Crude Birth Rate is the number of births per year per 1000 people.  Demographers can use this measure to estimate population growth.

Crude Death Rate

The amount of death in a society can be estimated using the Crude Death Rate which is the number of deaths per year per 1000 people.

Life Expectancy

Life expectancy is the average number of years a person can expect to live given the current mortality levels.

Average Age

The average age of a population is determined by adding up the ages of each individual in a population and dividing that sum by the number of people in a population.

A.     Fertility

Fertility explores the level of reproduction in a society. It refers to the number of children born to a woman.

Fecundity refers to the physical ability to reproduce.

Demographers distinguish between population increases that happen because of fertility (or natural increase) and increases that happen because of migration. Keep in mind that population growth will be negative if more people are dying that are being born.

The populations of some countries in Europe have entered a negative growth period. Their populations are declining because of changes in fertility patterns.   Women are not having children at the replacement rate. Each man and woman needs to reproduce themselves to maintain a stable population. On the other hand some countries are highly pronatalist (e.g., Iraq).

B.     Mortality

The second demographic variable, mortality, refers to dying. This discussion includes a historic component, an age component, and a genetic (sex linked) component.

1.     The Historic Component

a.     Disease

Historically, disease determined mortality levels. In the U.S. during the 1800s the major cause of death was disease, such as smallpox or the plague. Today, because of better health conditions and better medical care, disease has ceased to be an important issue (except in the realm of AIDS).

b.     Degenerative

The major causes of death are now degenerative problems like heart disease.

QUESTION: Death associated with cancer is on the rise. Why is the number of deaths attributable to cancer increasing?

People are going to die because of something.  When a society controls death in other areas (e.g., disease and heart attack), then the population will die from those ailments that have not been controlled (e.g., cancer)

2.     Age Related:

Age impacts mortality levels early and late in life. Congenital health problems influence morality rates early in life.

a.     The Very Young

Death rates for infants are higher than death rates for older children. One explanation is that infants are less resistant to disease.

Example: Infant Mortality in the United States

The Hunger Project (Hunger Action Forum, October 1988) points out that infant mortality is not a health problem, it is a social problem with health consequences. The U.S. ranks 19th among industrialized countries in infant mortality. Each year 40,000 infants die and 11,000 are born with low birth weights and long-term disabilities.

Europeans are much more successful in lowering their infant mortality rates. Differences between Europe and the U.S. in care of infants involve social programs in all countries. Europe has paid maternity leave (in West Germany and Norway fathers can take the maternity leave). There are also stringent limits placed on the types of working conditions pregnant women are allowed to work in. The state also provides maternity grants to families upon the birth of a child.

Such programs are initially expensive, but ultimately save money in terms of potential expensive health care in future and services to the developmentally disabled whose condition is linked to poor pre- and post-natal care.

Note: Infant Mortality Rate equals the number of deaths to people less than one year old per 1000 born.

QUESTION: When life expectancy rates increase, the average age of the population might become younger. WHY?

When life expectancy increases, it does so because death is controlled at the beginning of life. Babies will live longer, but all those babies will bring down the average age of the population.

b.     Teenagers

Teens tend to die from accidents

c.     The Elderly

The elderly suffer from degenerative problems.

3.     Mortality Rates and Differences in Gender

Men have lower life expectancy rates than women, but the gap is narrowing slightly.  Several aspects drive differences in mortality rates between men and women.

QUESTION: Why do women out-live men?

The Declining Birth Rates for Boys

Science News (April 4, 1998: 212) notes that there are 125 boys conceived for every 100 girls. Only 106 boys are born for every 100 girls. Stillbirths and miscarriages, therefore, disproportionately cull boys."

Recent trends in sex-ratios suggest that the number of boys born, as a proportion of girls, is on the decrease. Canada experienced a drop of 2.8 male births per 1000 births. The trend in the United States was more like a drop of 1 male birth per 1000 births. Holland and Denmark have reported similar trends.

Science News argues that this trend can be explained by looking at the environment. Fertility stimulating drugs can account for a small part of the increase in female births. The real culprits are probably "ubiquitous hormone-like pollutants" like Dioxin. Science News makes reference to an industrial accident in Seveso, Italy in 1976. After that accident 12 daughters and no sons were born to parents who had a high level of Dioxin in their blood.

C.     Migration

The third way population's change is by migration. In the United States, migration refers to any permanent change of residence outside the county in which an individual currently resides. An American migrates an average of seven times during his or her life. From 1970 to 1980, 41 percent of all Americans migrated at least once.

QUESTION: What is the difference between emigration and immigration?

Immigration refers to people moving in and emigration refers to people moving out.

QUESTION: Why do people move?

People move for jobs more than any other reason.

QUESTION: Who Moves?

Young people between the ages of 20 and 30 are the most Mobil.

QUESTION: What is the educational level of people who migrate?

Compared to the people in a population who don't migrate, migrants a have higher levels of education.

QUESTION: What is the motivational level of people who migrate vs. those who do not?

Obviously, people who move are more motivated than those who do not.

QUESTION: How does out migration affect the donor area?

The donor area is adversely affected.  They lose young, motivated, and education people.  Plus the donor area loses the investment in those individuals.  It costs the community resources to raise a young, motivated, educated worker.  The community loses that investment.

QUESTION: How does in migration affect the recipient area?

The recipient area gets a young, motivated, and educated citizen and has to pay nothing for that person's development.

QUESTION: What is the flow of migration within the United States?

People are moving from North to South and from the center of the country to the periphery.

QUESTION: True or false, the 1980s have seen the greatest level of immigration in the past 100 years.

False!  The U.S. had greater numbers of immigrants from 1900 to 1910 than in the 1980s.  Further, the U.S. population was much smaller that it is now, so the proportion of the population that were of immigrant stock was nearly double current levels.

V.     Demographic Perspectives

Demographic perspectives are ways of relating basic population information to theories about how the world operates demographically. Demographic perspectives affect the way we interpret the relationships between populations factors such as size, distributions, age structures, and growth. Demographic perspectives are concerned with the causes of population growth and the consequences of that growth.

A.     The Malthusian Prospective

1.     Causes of Population Growth

Thomas Malthus was a minister who used religious teachings to build his population policy. He believed that people have an innate urge that impels them to reproduce. According to Malthus, if people did not learn to control their vices then overpopulation would occur and bring on the fall of humanity. Malthus felt that if population growth remained unchecked, human beings could populate millions of worlds in a few thousand years (see Weeks, 1996:63-69).

There are two solutions for controlling population. Malthus calls them "checks." There are preventive checks and positive checks.

a.     Preventive Checks

Preventive checks would include abstinence from sexual intercourse and postponing marriage until after twenty-five years old. Malthus would not condone modern birth control techniques. The only appropriate method of birth control was postponing marriage and abstaining from sex.

b.     Positive Checks:

Positive checks would include war, famine, pestilence, and disease (Sounds like the four horsemen!). Food production (or lack of it) is a central positive check. Populations, according to Malthus, expand geometrically. Food production at best expands arithmetically. At this rate, population growth rapidly outstrips food supplies.

2.     Consequences of Population Growth: Poverty

For Malthus, the natural consequence of population growth was misery, starvation, and poverty, but if people remained poor it was their own fault.

3.     Avoiding the Consequences

Malthus thought if the poor were allowed to feel the "great pain" of poverty, then the poor would take steps to avoid the "great pain" by having smaller families. He was totally against welfare programs because welfare would prevent the poor from feeling the "great pain" of poverty.

4.     Critiques of Malthus

Critics of Malthus focus on primarily three aspects of Malthusian theory.

a.     Food Production and Population Growth

Noting that Malthus lived at the beginning of the industrial revolution is important. He had no way of knowing that industrialization would provide the ability to mass produce food. He personally had little faith in the longevity of the industrial revolution.

b.     Moral Restraint

The implied assumption embedded in the moral restraint doctrine of Malthus is that the poor are the ones who are immoral and the rich are not.

An interesting and unintended consequence of Malthusian doctrine is that it helped spread the knowledge of contraceptives although he was against it.

c.     Is Poverty Inevitable?

Poverty is the cause of overpopulation, not the consequence. Economic development reduces population because people no longer have to depend, exclusively, upon their children for social support. Improving economic status decreases' population growth.

5.     Modern Malthusians

Modern Malthusians, such as Paul Ehrlick, the author of The Population Bomb, are more open toward the idea of "the pill" and abortion. Rather than moral restraint, modern Malthusians might advocate a variation called prudent restraint. For example, modern Malthusians might advocate waiting to have a family until one can afford it.

B.     Demographic Transition

1.     The Three Phases of Demographic Transition

One of the most popular population theories is demographic transition (Weeks, 1996:77-80). It is a model that explains population dynamics of European / American industrial societies. It traditionally is presented in three phases.  As a society industrializes, birth rates will decline because children in an industrial society present more of an economic burden to their parents when compared to children in preindustrial society.

a.     Phase One:

High birth and high death rates characterize the first phase of Demographic Transition. Examples of nations that are in the first phase are Ethiopia, Angola, and Nigeria.

b.     Phase Two:

High birth rates also characterize the second phase of demographic transition, but so do low death rates. Death rates decline because of better health conditions, improved medicine, better food, etc. Nations that are in the second phase include most of today's Third World countries.

Rapid population growth (or population explosion) occurs in the second phase of demographic transition.

c.     Phase Three:

Low birth rates, low death rates, and a stable population characterize the third phase. This phase includes most of Europe, Japan and The United States. Parents are encouraged to keep families small, in part, because children become an economic burden in advanced industrial societiesPeople are less dependent on their children as a personal labor force.  Later in life, the state provides for social security.

2.     Demographic Transition: An Economic Explanation of Population Dynamics

Demographic Transition is a population theory that relates economic development to patterns of population growth. The general position of Demographic Transition is that if people feel economically secure, then the population growth will slow. In other words, through industrialization, people obtain a better standard of living and a better standard of living encourages smaller families. To pass the "good life" on to their children, parents keep their families small. It makes sense! (Middle-class necessities, like a university education, are expensive. Therefore, families with several children find it more difficult to send all of their children to college.

For much of the industrial world, the demographic transition model may be a good predictor of how populations in the world change. There are signs, however, that much of the Third World is not following the industrialized nations into the final phase of Demographic Transition. Some nations have gotten "stuck" in the second phase. Countries that continue to experience high birth rates and low death rates might drop back into the first phase that means that death rates will go up dramatically.

C.     Marxist Perspectives on Population Growth

1.     A Response to Malthus

Marxists are specially resisted the anti-humanitarian aspects of Malthus (see Weeks, 1996:69-72).

2.     No Eternal Laws of Population Dynamics

Marxists, who theorize about population, tend to argue there are no eternal or natural laws that govern population growth. According to Marxists, each society has its own laws of population dynamics.

3.     Population and Poverty

According to the Marxist perspective the idea of limiting population is a capitalist idea in the first place. Limiting population becomes necessary because so much wealth comes to be concentrated in the hands of a few. Only in capitalist societies does population growth yields overpopulation and poverty.  They argue that capitalism, not too many people, causes social problems like poverty.

In an efficient socialist state, more people should yield more wealth. Engels maintained that each birth meant that there were two more hands to produce for society. Advances in science and technology should enable food supplies to keep up with population growth.

Example: India and China

India and China represent two societies where, despite their being the largest countries in terms of population on earth, they have moved from the brink of starvation to near self-sufficiency in grain.

VI.     Structural Considerations Affecting Population Policy

A.     What is Dependency?

Demographers make the assumption that most of the people between the ages of fifteen and sixty-five are working and that people between the ages of zero to fifteen and sixty-five and over are dependent on those who work. People view children and the elderly as dependent on those who work (Weeks, 1996:257).

B.     Dependency within the Family

Compare two families with equal resources. One family, however, has two children while the other family has ten children. The family with ten children has to spend more of the family resources on providing essentials for the family's survival (food, shelter, etc.). A smaller family does not have to spend as much as the larger family on necessities. The extra money can be used to build security (savings account, a new car, new house).

C.     Dependency at a National Level: Dependency Ratios

Nation states experience the same problems that families do when the number of dependents in the population is too large compared to the number of people who are available to support those dependents.  Dependency ratios describe the relationship between workers and dependents. In countries with high rates of dependency, money that should be directed toward building an infrastructure has to go toward feeding babies and supporting an excess population. In Third-World settings factories are needed to hire the unemployed. High dependency ratios mean that money is being directed toward support of dependents and not toward the development of the infrastructure. What infrastructure that is already in place experiences even greater strain as population pressure increases.

(Dependency Ratio =  Dependents / Workers)

Example: Dependency in the U.S. and Mexico

In the 1980s, forty percent of Mexico's population is less than fifteen years old. The dependency ratio is an index used to measure the social and economic impact of different age structures (See Weeks, 1981:188). Dividing the dependent population by the working population determines it. In 1980, the dependency ratio for Mexico is .88. The dependency ratio for the United States is .52.

Example: Asians in America

Why do Asian-Americans prosper? They have small families and spend heavily on each child for things like a college education.

D.     Small vs. Large

Notice the problem that a country with a large population has in bringing its population under control. This calls attention to the Rate Vs. Base issue in demographics. Population growth rates have to come down, but in some countries, the base is so large that population continues to expand. People tend to be lulled into quietude because the rates have dropped, but the base remains large.

In China, a one percent annual growth rate in the population adds ten million people per year to the population. If a country like Nicaragua, on the other hand, which has a population of only two million, a growth rate as high as 10 percent would only add 200,000 to the population.

E.     Zero Population Growth (ZPG): Now vs. Later (1.8 kids/family =ZPG)

ZPG is achieved when births and immigration = deaths and emigration (See Weeks, 1996:279-288)

Why doesn't a country, like China, simply outlaw births for five or ten years? Such a move would reduce population size immediately, but it would adversely affect other social structures. Remember the Baby Boom example. Shock waves of population have negative effects on the rest of the social structure.

QUESTION: What if China was to outlaw babies for five years? What would that do to their social structure?

The Chinese social structure would be overwhelmed, much as the U.S. social structure was during the 1950s.  The effect, however, would be more pronounced.  First institutions would suffer a baby recession as no babies would enter the population for five years.  There would be no first grades for five years, high schools would be completely without students for a couple of years, and the military would have no new recruits for five years.  Then after the baby-ban is lifted, everyone would have kids producing a baby boom.  The method of slowing bringing down the birth rate is probably the most effective long-term strategy.

VII.     Cultural Factors Affecting Population Policy

Despite tremendous population pressures in the world, a variety of culture factors act to keep birth rates high. Cultural factors that might act to mitigate population control efforts include:

A.     Distrust of Doctors

Family planning efforts inevitable involve visits to clinics and doctors.  In many developing countries, doctors are rare.  Many doctors that are present are from first-world countries.

B.     Ignorance of Biological Facts

In order to prevent births (assuming one wants to), potential parents have to be aware of the biological process that creates babies in the first place.

C.     A Desire for Sons

The desire for sons is a major impediment to birth control programs.

D.     The Emotional Conditioning of the Male

In many cases large families equal status for the males.  A large family is living proof of the virility of the male.

E.     A General Problem

People act, not for the good of society, but for their own immediate needs. In order for a population policy to be effective, individuals have to be convinced that they (and their family) will benefit.

VIII.     Population and Poverty

Population growth in the Third World threatens to exceed the carrying capacity and overwhelm gains achieved through economic growth. The United Nation predicts that the population in areas like Central America will increase 120 percent over the next thirty years. The population density of El Salvador is nearly as great as that of India. According to the Population Reference Bureau (1998), the density per square mile in El Salvador while it stands at 861 in India. Rapid population growth inhibits economic development. As population increases, income must grow just to maintain current standards of living. If population growth exceeds economic development, standards of living fall. In this respect population growth causes poverty.

Nancy Birdsall (1980) of the World Bank acknowledges that high population growth increases the incidence of poverty, but she argues that, in more dramatic fashion, poverty encourages population growth.

A.     Economic Growth Causes Birth Rates to Decline

Economic growth may be a key to reducing both poverty and population growth.  Economic growth encourages what Birdsall (1980) calls a "fortuitous cycle" in that living standards improve and population growth rates decline.

B.     The Malthusian Trap

Unfortunately if income growth does not keep up with population growth, the fortuitous cycle may turn vicious. World Watch (1987) doubts the ability of the world to continue rapid economic expansion. Kingsly Davis (in PTPP, 1983) argues that given the present state of Third World population growth, it is already too late to address population growth through economic development. Merrick (1986) warns of a "Malthusian trap." Malthus warned a couple of hundred years ago that if people did not control population through preventative check, the population problem would be dealt with through positive checks.  Positive checks are called positive, not because they are desirable, but because they work.  War, famine, pestilence, and disease will reduce population size.  Humanity encounters the Malthusian trap when the population becomes so large that "prevention" is no longer possible in bringing population growth under control.  The only solution then is the positive check on population.

The population growth rate, according to Merrick, is already too great. There are no more frontiers that can absorb excess population. If this scenario is correct, death rates should begin to rise in countries where population growth out paces the economy (See Africa).

Example: Where Do We Control Population?

Third World countries have many more people than do First World Countries. However, First World Countries often consume more resources than do Third World Countries. India has over a billion people while the U.S. has only 300 million people. Indians per capita, however, consume 1/16 the resources that Americas consume. Each American added to the world population has a greater impact on the ecology of the planet than each Asian that is added. The reason is that Americans consume many times more resources than Asians.  In terms on conserving resources perhaps population growth is more detrimental to the environment in First World countries.


Birdsall, Nancy

1980 "Population Growth and Poverty in the Developing World." Population Bulletin. 35(5):1-48.

Bouvier, Leon F. and Robert W.Gardner

1986 "Immigration to the U.S.: The Unfinished Story" Population Bulletin, 41(4):1-50.

Ehrlick, Paul

The Population Bomb.

Hager, Mary

1998 "How Demographic Fatigue Will Defuse the Population Bomb." Newsweek. November 2.

Hunger Action Forum

1988 (October 1988)

Kingsly Davis

1983 "Population Change, Resources, and the Environment." Population Trends and Public Policy, (December) 4: 1- 16.

Merrick, Thomas W.

1986 "Population Pressures in Latin America." Population Bulletin, 41(3): 1-51.

World Population Data Sheet

1985 "World Population Data Sheet." Washington, D.C.: Population Reference Bureau.

1987 "World Population Data Sheet." Washington, D.C.: Population Reference Bureau.

1988 "World Population Data Sheet." Washington, D.C.: Population Reference Bureau.

1990 "World Population Data Sheet." Washington, D.C.: Population Reference Bureau.

1993 "World Population Data Sheet." Washington, D.C.: Population Reference Bureau.

1998 "World Population Data Sheet." Washington, D.C.: Population Reference Bureau.

2000 "World Population Data Sheet." Washington, D.C.: Population Reference Bureau.

2003 "World Population Data Sheet." Washington, D.C.: Population Reference Bureau.

2006 "World Population Data Sheet." Washington, D.C.: Population Reference Bureau.

Science News

1998 (April 4, 1998: 212)

Weeks, John R

1996 Population: An Introduction to Concepts and Issues. (6th Ed.) Belmont: Wadsworth Publishing Company.

White, Richard Alan

1984 The Morass: United States Intervention in Central America. New York: Harper & Row.

World Development Forum

1988 "The Latin Block on Land Reform" World Development Forum 6(9):1-4.

World Watch

1987 State of the World. New York: W.W. Norton.