The crude death rate or CDR is the ratio of the number of deaths yearly per 1,000 people in a given population.

The stationary population level (SPL) is the level at which a population cannot grow any more.

Demography is the study of human population. Specifically, demography generally involves the study of statistics concerning things like birth and death rates, fertility and public health, income, ethnicity, and outbreaks of disease.

All of these countries are in either stage two or stage three (the transitional stages) of the demographic transition model, except Japan, which is in stage four. Stage four is generally considered the final stage of the demographic transition model. In stage four, the birth rates and the death rates are both low and generally steady. In Japan, the death rate is very low and the birth rate is very low, leading to a steady population and perhaps even a slight population decline.

In highly developed countries like the United States the natural increase rate is generally very low, it might even be negative. But, the natural increase rate only reflects the changes in population caused by births and deaths; it does not consider immigration and emigration. Much of the population growth in the United States is driven by immigration and the fact that newly arrived immigrants are much more likely to have large families.

Malthus’ “principle of population” states that eventually, population growth will exceed the capacity of agricultural production, which will lead to widespread starvation and suffering. Over the years, many detractors have proposed various arguments in opposition to Malthus’ theories. Two of the most prominent arguments are that a) population growth will slow due to the availability of contraception and the desire of governments to limit growth and b) technological innovation can lead to dramatic improvements in agricultural production, which allow it to keep up with the growth in population.

The natural increase rate does not consider immigration or emigration. It is determined by subtracting the number of deaths from the number of births in a given region. So, if there are ten thousand deaths and thirteen thousand births in a given region, in a given time period, the natural increase rate is three thousand.

A population pyramid is used to show the percentage of the population who fit into various age groups. If a population pyramid is rectangular, that means the bottom section (where babies are represented), the middle section (where working adults are represented), and the top section (where older people who are often retired are represented) are roughly similar sizes. This generally means the population of a country is close to steady, but is possibly growing slightly. A country like Norway or the United Kingdom would have a rectangular population pyramid.

Most geographers and demographers agree that over the course of the twenty-first century, the population growth will slow considerably. This is based on the belief that the current rapid population growth is an anomaly in Earth’s history and that the planet cannot sustain such rapid growth for another century.

The Natural Increase Rate and the Demographic Accounting Equation are both calculations used to determine the current or projected population growth of a region. The Demographic Accounting Equation is more comprehensive because it takes into account immigration and emigration, whereas the Natural Increase Rate only takes into account the birth and death rates.