UNIT 3

• birth rate : total number of live births per 1000 of a population over a year 
• death rate: number of deaths in a population in a year 
• natural increase: is the number of births minus the numbers of deaths
• infant mortality rate : is the number of deaths infants under one year dividing thenumber of births over a year ,per 1000
• life expectancy : is the average years that one person is expected to live 
• fertility rate :is the number of live births by the number of woman ages 15 - 49 in a year per 1000
• dependent population: Group of people who are unemployed looking for their first job, studying or carrying  out non remmunerated household chores
•   Dependency ratio : meausure showing the number of dependents , aged zero to 14 and over the age of 65, to the total population , aged to 64 
• Family planning:is the practice of controlling the number of children in a family and the intervals between their births, particularly by means of artificial contraception or voluntary sterilization
• MEDC: more economically developed country 
• LEDC: less economically developed country
• Population piramids/age-gender structures: graphical illustration that shows the distribution of various age groups in a population, which forms the shape of a pyramid when the population is growing

• Replacement rate: percentage of a worker's pre-retirement income that is paid out by a pension program upon retirement
• Fertility rate: ratio of live births in an area to the population of that area; expressed per 1000 population per year 
• Ageing population: phenomenon that occurs when the median age of a country or region increases due to rising life expectancy or declining fertility rates.
• Overpopulation: situation in which too many people or animals live in an area

Underpopulation: population lower than is normal