Permanent Population

refers to the total number of people alive at a given area over half year. According to the regulation of population census and sample survey, permanent resident population include (1) registered population in this area except those who have left this area over half a year (exclude those going abroad to work or study). (2) population with residence registered in other area, but having actually resided in this area over half a year or having left place of residence registration over half a year and resided in this area during the period of population survey. (3) population with residence registration in this enumeration area not yet settled, i.e. residence card on hand, migration certificate, birth certificate, demobilized soldier card, release certificate, etc.

Population Density

refers to the total number of people within unit land area. Usually, population density is calculated with permanent resident population and indicates crowd degree of population. It is often expressed in the number of people per square kilometer. The following formula is used:

Population Density =	Permanent Resident Population
	Total Area of Land

Birth Rate (or Crude Birth Rate)

refers to the ratio of the number of births to the average population (or mid-period population) during a certain period of time (usually a year), expressed in ‰. Birth rate in the chapter refers to annual birth rate. The following formula is used:

Birth Rate =	Number of Births	×1000‰
	Annual Average Population

Number of births in the formula refers to live births, i.e. when a baby has breathed or showed any vital phenomena regardless of the length of pregnancy. Annual average population is the average of the number of population at the beginning of the year and that at the end of the year. Sometimes it is substituted by the mid-year population.

Death Rate (or Crude Death Rate)

refers to the ratio of the number of deaths to the average population (or mid-period population) during a certain period of time (usually a year), expressed in ‰. Death rate in the chapter refers to annual death rate. The following formula is used:

Death Rate =	Number of Deaths	×1000‰
	Annual Average Population

Natural Growth Rate of Population

refers to the ratio of natural increase in population (number of births minus number of deaths) in a certain period of time (usually a year) to the average population (or mid-period population) of the same period, expressed in ‰. The following formula is applied:

Natural Growth Rate of Population =	Number of Births - Number of Deaths	×1000‰
	Annual Average Population

Natural Growth Rate of Population = Birth Rate - Death Rate

Gross Dependency Ratio

refers to the ratio of children aged 0-14 and elderly population aged 65 and over to the working-age population aged 15-64. It describes in general the number of non-working-age population that every 100 people at working ages will take care of. The following formula is used:

Gross Dependency Ratio =	(Population Aged 0-14) + (Population Aged 65 and over)	×100%
	Population Aged 15-64

Legal Marriage Age, Labour Age Population

The standard of legal marriage age is 22 for male and 20 for female. The domestic standard of “reaching labour age”, “within labour age” and “over labour age” are 16, 16 to 59, 60 for male respectively and 16, 16 to 54, 55 for female respectively; the international standard of these items are 15, 15-64 and 65 respectively for both male and female.