Based on different research perspectives, scholars at home and abroad have made different attempts to quantitatively describe population quality. There are three representative models to measure the quality of population: PQLI, ASHA and HDI: material quality of life index (PQLI) is a comprehensive index proposed by M. D. Morris in 1975, which is used to comprehensively measure the progress of a country's people in the fields of nutrition, medical care, national education and other material welfare. Its main purpose is to reflect a country's achievements in meeting people's basic needs.
In the book "Development Economics", PQLI is the "material quality of life index", which means that a country's life expectancy, infant mortality and literacy rate are divided into percentiles, and the comprehensive material quality of life index PQLI of this country is calculated with the same weighted average.
Definition variables: kwtb mi is the infant mortality index, LEI is the life expectancy index, l Ⅱ is the literacy index, PSBD is the actual number of deaths per 1,000 infants, PLM is the number of literates in the population above 15, and TM is the total population above 15.
From the above index selection and calculation methods, we know that the three indexes selected by PQLI index mainly involve physical fitness, which can better reflect the quality of the population in a society with low degree of industrialization, and the index selection is simple and easy to operate. However, the defects of PQLI index in reflecting population quality are also obvious. First of all, the index covers a very narrow range, only two major areas, physical and intellectual, which is not enough to comprehensively analyze and understand the quality of the population; Secondly, only using adult literacy rate as an indicator of cultural quality can not reflect the cultural and educational level of the population; Thirdly, PQLI index is mainly suitable for evaluating the quality of life of residents in developing countries, and its application in countries is greatly limited; In addition, the simple average method is adopted in the process of index synthesis, that is, the equal weight method of each index in the model is adopted. In fact, the importance of each index in the model is not only different, so the PQLI model method has practical limitations.
PQLI population quality index is superior to other population quality index systems. First of all, its research object is countries with relatively low degree of industrialization, similar to the situation in China; Secondly, the PQLI index is relatively simple, which is also beneficial for researchers to analyze data. The index was put forward by the American Society for Social Health (ASHA), which is mainly used to reflect the social and economic development level of a country, especially developing countries, and the achievements made in meeting people's basic needs.
Define variables: ER stands for employment rate, LI stands for literacy rate and average life expectancy index, PGNPID stands for per capita GDP growth rate, PB stands for population birth rate and BMR stands for infant mortality rate and average life expectancy. Before calculating the index, the average life expectancy index is converted into exponential form. The indicators selected by ASHA index are representative, and the comprehensive method of multiplication and division is scientific and reasonable, but there are still some limitations in the use of population quality, mainly as follows: the indicators selected are more inclined to social indicators, while economic indicators and their cross indicators are less considered; (2) The indicators are not standardized; ⑶ It is considered that each index has the same influence on the whole, there is no weighted average, and the different weights of each index are not distinguished. Moreover, the comprehensive method of multiplication and division makes the change of index value too sensitive to each index, especially the small change of index value has too prominent influence on the index. The Human Development Index (HDI) was first put forward in the Human Development Report 1990 published by the United Nations Development Programme (UNDP). The index mainly discusses the definition and measurement of human development, the relationship between economic growth and human development, and the human development strategy in the11990s. Mainly as a comprehensive index to measure the poverty reduction degree of developing countries. The index selects life expectancy, adult literacy rate and real per capita GDP calculated at purchasing power parity to evaluate a country's development level, and its calculation formula is:
That is, the three indicators of each country are indexed (dimensionless), and each index takes the extreme value range of the indicator in the country as the denominator and the difference between the maximum value of the indicator and the actual value of the indicator in a country as the numerator.
Taking HDI as a comprehensive evaluation index of human development level undoubtedly provides a new way of thinking for people to evaluate the level of social development. However, it is not comprehensive to evaluate a country's population quality only by selecting three indicators: life expectancy, adult literacy rate and real per capita GDP calculated at purchasing power parity. Moreover, these three indicators are only related to health, education and living standards, and cannot fully reflect the development of population quality. Secondly, according to relevant research, there is a high positive correlation between HDI and its constituent indicators; Thirdly, there is also a lack of corresponding theoretical basis in the selection of maximum and minimum values.