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	Demography
	Daniel Udovic, Jasper Barber, Will Goodwin, and Gordon Hennesy (University of Oregon)
Screen Shots | What's New | System Requirements

Why are human populations in Africa growing so rapidly, even though life expectancy is shorter than in most other parts of the world? Why do rapidly growing populations have such a large proportion of children? Why is the population of China still growing, even though the government is enforcing a "one-child per couple" population policy?

These are a small sample of the kinds of questions that can be addressed by using Demography, an application that simulates exponential growth in age-structured populations. By manipulating values for age-specific mortality rates, fertility rates, and initial population characteristics, and using the simulation to see how population characteristics change through time, users of Demography can investigate important questions in population biology, develop a deeper understanding of fundamental population concepts, and explore issues related to population policy.

Demography displays fertility and mortality graphically as functions of age. The Current Age Distribution window displays the percentage of the total population in each age interval in the form of an age pyramid. Three other windows (Summary Statistics, Survivorship vs Age, and Stable Age Distribution) display data that are directly derived from the fertility and mortality graphs.

A key feature of Demography is the easy-to-use interface that allows you to rapidly and intuitively alter population characteristics, even while a simulation is running, and to instantaneously see the effects of your alterations. For example, changing the mortality rate of a particular age group, such as 20-25 year-olds, can be done by simply manipulating a point on a graph using the mouse. As soon as you release the mouse button, Demography will recalculate important population statistics, such as longevity (mean life expectancy) or doubling time.

Screen Shots

The Current Age Distribution window.

The Mortality vs Age window.

What's New?

Version 4.1 of Demography includes these new features:

• Immigration/Emigration - allows the use of immigration into the population, and emigration out of the population.
• Density-Dependent Model - includes a density-dependent model of growth. Individuals in the population are assumed to be competing for a single, potentially limiting resource.
• New Activities - a new set of activities, called "Exploring Demography.

System Requirements

Macintosh or Power Macintosh

• System 6.07 or later; System 7.1 or later for Power Macintosh. System 7.1 is recommended.
• At least 1 megabyte of available RAM.