Recently Science had a special issue examining many aspects of population: "the opportunities and challenges created by demographic changes around the world." One of the Science articles, "The Outlook for Population Growth" by Ronald Lee, has the abstract:
Projections of population size, growth rates, and age distribution, although extending to distant horizons, shape policies today for the economy, environment, and government programs such as public pensions and health care. The projections can lead to costly policy adjustments, which in turn can cause political and economic turmoil. The United Nations projects global population to grow from about 7 billion today to 9.3 billion in 2050 and 10.1 billion in 2100, while the Old Age Dependency Ratio doubles by 2050 and triples by 2100. How are such population projections made, and how certain can we be about the trends they foresee?
In the article Lee notes that he uses the terms population "projections" or "forecasts" interchangeably.
One of the works Lee cites is Demographic Forecasting. The work emphasizes statistical methods for forecasting population death rates. It has the LCSH Mortality—Forecasting—Methodology, Mortality—Statistical methods, and Demography. Browsing the Relative Index for "mortality" yields:
Browsing the Relative Index for "forecasting" yields:
Browsing the Relative Index for "statistical methods" yields:
Statistical methods 001.422
Statistical methods T1—0727
. . . . .
Statistical methods—systems analysis T1—011
In the table of preference at the beginning of Table 1, T1—07 appears above T1—01. However, at T1—0727 Statistical methods is the class-elsewhere note "Class statistical methods used in systems analysis in T1—011." That note is relevant because the interdisciplinary number for forecasting (003.2 Forecasting and forecasts) is a subdivision of 003 Systems, where systems analysis appears in a class-here note. Since class-here notes have hierarchical force, the note applies as well at 003.2. The work Demographic Forecasting is classed in 304.640112 Forecasting and forecasts of deaths (Forecasting and forecasts of mortality), built with 304.64 Deaths (Mortality) plus T1—011 Systems plus 2 from 003.2 Forecasting and forecasts, following the add instruction at T1—011 Systems.
Another work cited by Lee is The End of World Population Growth in the 21st Century: New Challenges for Human Capital Formation and Sustainable Development. It has the LCSH Population forecasting, Twenty-first century—Forecasts, and Demographic transition. The work treats forecasts and forecasting of population growth and shrinkage. Browsing the Relative Index for "population" yields:
One of the subdivisions of 304.6 Population is 304.62 Growth and decline. Browsing the Relative Index for "twenty-first century" yields:
Twenty-first century 909.83
Twenty-first century T1—0905
In the table of preference at the beginning of Table 1, T1—01 comes before T1—0901–T1—0905; hence T1—0112 Forecasting and forecasts is generally to be preferred over T1—0905 21st century, 2000-2099. The add instruction at T1—011 Systems describes exceptions to that general preference, but the exceptions are all limited to "short-term forecasts (ten years or less)." The exceptions do not apply to The End of World Population Growth in the 21st Century, which treats the full century. Hence that work is classed in 304.620112 Forecasting and forecasts of population growth and decline, built with 304.62 Population growth and decline plus T1—011 Systems plus 2 from 003.2 Forecasting and forecasts, following the add instruction at T1—011 Systems.
One of the starting points for forecasting population is the demographic data from a census (a periodic survey of a population of a specific area). In a previous blog, "United States Census," we described the DDC numbers used for a census.