Forecasting Population Size Based on Certain Criteria

Forecasting Population Size Based on Certain Criteria : Age structure - classifies members of a population into groups according to age or the distribution of members of a population in age groups helps demographers make predictions

high rates of growth = more young people slow growth or no growth = even distribution of ages

Population Pyramid a graph showing majority of ages of people in the population predicts if and when the population will grow 4

Population Pyramid Age of population

What is the overall shape of the graph? Is there a dominant age group or groups? What proportion of the 0 - 4 age group survives into the elderly (60+) age groups? Are the male and female sides roughly equal?

Age-Structure Diagrams

Activity Reading and analyzing a Population Pyramid Graph. Textbook: Page 220 Answer the questions pertaining to this graph.

Forecasting Population Size continued… 2. Survivorship: Percentage of newborn individuals in a population that are likely to survive to any given age Demographers note birth and then the death groups

Types of Survivorship Curves Varies from country to country. Developed countries have higher survival rates. Why? Types of Survivorship Curves Type I - most people live to be very old Type II - have a similar death rate at all ages Type III - many offspring die Both Type I and Type III may result in populations that remain the same size or grow slowly.

3. Fertility Rates: -Number of babies born per year per 1000 women. -Replacement level is the average number of children each parent must have in order to “replace” themselves. Change in population = births – deaths

Fertility Rates

Migration: movement of individuals from one area to another Immigration: moving into an area Emigration: moving out of an area

Migration between and within countries is a significant part of population change.

Life Expectancy Average number of years a person is expected to live. Most affected by infant mortality - death rate of children less than 1 yr. old Affected by parents’ education food fuel clean water population density disease

Life Expectancy in USA

The Demographic Transition the general pattern of demographic change from high birth and death rates to low birth and death rates observed historically in more-developed countries industrial development causes economic and social progress that then affects population growth rates

Stages of the Transition

Stage 1 - Preindustrial high level birth rate and the death rate population size is stable

Stage 2 - Transitional population explosion occurs death rates decline hygiene, nutrition, and education improve birth rates remain high population grows very fast

Stage 3 - Industrial population growth slows birth rate decreases population size stabilizes but larger

Stage 4 - Postindustrial birth rate drops below replacement level population size decreases

Women and Fertility Women who have fewer children are: Those who know family planning techniques Independent Educated

Activity Section Review questions page 231 Answer every question in a complete sentence.