Spatial Network Structures of Urban Agglomeration Based on the Improved Gravity Model: A Case Study in China’s Two Urban Agglomerations

Table 1

Urban agglomeration centrality evaluation index system.

Subsystem	Indicators	Unit	Reference
Population size	Total population	Ten thousand	[32, 38, 39]
	Natural population growth rate	%
Economic aggregate and structure	GDP	Ten thousand yuan	[37–39]
	Industrial output value above designated size	Ten thousand yuan
	Investment in fixed assets	Ten thousand yuan
	Public revenue	Ten thousand yuan
	Proportion of tertiary industry	%
Economic benefits and foreign investment	GDP growth rate	%	[30, 31]
	GDP per capita	Yuan
	Per capita financial income	Yuan/person
	Actually utilized foreign capital in that year	Ten thousand US dollars
Resident life	The total retail sales of social consumer goods	Ten thousand yuan	[29, 30]
	Public expenditure	Ten thousand yuan
	Average wage of urban employees	Yuan
	Deposit balance per capita of financial institutions	Yuan
	Per capita disposable income of urban residents	Yuan
	Number of people participating in basic pension insurance for urban employees	Person
Science, education, culture, and health services	Number of ordinary college students per 10,000 people	Person	[29, 31]
	Education expenditure	Ten thousand yuan
	Number of full-time teachers in ordinary universities	Person
	Number of hospital beds	Bed
	Doctors per 10,000 people	Person
	Library collection per capita	Volumes
	Patent application authorization	Item
Traffic communication	Urban road area per capita	Square meter	[29–31]
	Total post and telecommunication services	Ten thousand yuan
	Number of mobile phone users at the end of the year	Ten thousand households
	Number of Internet broadband users	Ten thousand households
	Number of bus operations	Vehicle
	Highway mileage	Kilometers
Infrastructure	Built-up areas	Square kilometers	[29, 39]
	Drainage pipe density	M/m^2
	Water consumption per capita	Ton
	Road freight	Ten thousand tons
	Highway passenger traffic	Ten thousand persons
Waste disposal	Sewage treatment rate	%	[29, 39]
Urban afforestation	Green coverage	%	[29, 31]
	Per capita public green area	Square meter