Research on Innovation Efficiency of Listed Companies in Development Zone Based on the Three-Stage DEA-Tobit Model: A Case Study of Hubei Province

Table 1

Related indicators of innovation efficiency measurement.

Reference layer		Indicator layer
Innovation input variables	R&D	Technician
		R&D investment
	Production input	All employees of the enterprise
Innovation output variable	Technical output	Number of invention patents granted
	Marketing output	Total operating income
Environment variables	Number of companies	Number of listed companies in the industry
	Investment in fixed assets	Development zone investment in fixed assets
	Foreign direct investment	Foreign Direct investment in development zones
	Government subsidy	Government subsidies for listed companies