Variable

Unit

Symbol

Mean

Standard deviation

Minimum value

Maximum

Observations

Dependent variable

SO₂ emission intensity

Tons/100 million yuan

SI

50.4599

55.3349

0.2361

503.9894

689

Soot emission intensity

Tons/100 million yuan

MI

24.6857

64.1891

0.0453

1487.365

689

Independent variable

Yangtze River Delta

-

YRD

0.4906

0.5003

0

1

689

Pearl River Delta

-

PRD

0.2642

0.4412

0

1

689

Policy

-

Policy

0.3077

0.4619

0

1

689

Control variable

X

Per capita GDP

Yuan

PGDP

46699.16

37733.34

4111

467749

689

Industrial structure

%

STR

50.7073

8.2674

19.74

74.73

689

The population density

Person/km²

POP

618.1452

348.5712

90.79

2661.54

689

The level of urbanization

%

UR

0.4248

0.2634

0.0708

1.0101

689

Social capital

%

SC

0.2098

0.2759

0.0045

3.6635

689

Financial expenditure

Hundred million yuan

FE

372.8035

680.5838

9.2022

6191.56

689

R & D intensity

%

RD

0.0206

0.0196

0.0004

0.2068

689

Technical import

%

FI

0.0326

0.0216

0.0007

0.129

689