7.2 what factors influence population size?

populations can grow, decline, or remain fairly stable
人口改變＝（出生率＋遷入）-（死亡率＋遷出）
birth rate
death rate

women are having fewer babies but not few enough to stabilize the world population
fertility rate生育率
replacement-level fertility rate (2.1 to 2.5)
total fertility rate(TFR)1.6 to 2.9-台灣在95年總生育率已降至1.1

Case study- the U.S. population is growing rapidly
oscillation振動,擺動
homicide殺人犯
大多數已開發國家人口在2010開始減少，台灣預估在2018開始減少。

Several factors affect birth rates and fertility rates
1. importance of childern as a part of the labor force.
2. cost of raising and educating children.
3. availability of private and public pension退休金;養老金 systems
4. urbanization
5. educational and empolyment opportunities available for women
6. infant mortality rate
7. average age at marrage(first child)
8. availability of legal abortions
9. availability of reliable birth control methods
10. regligious beliefs, traditions, and cultural norms

Several factors affect death rates
food supplies and distribution 食物供給與分配（批發零售）
immunization免疫
curtail縮減,削減
incidence發生率
undernutrition營養不足
malnutrition營養失調，營養不良