Table 3 Code definition

\(i\)

Heavily polluting enterprises

\(t\)

Year

\(Y_{it}\)

Dependent variable

\(x_{it}\)

Independent variable

\(q_{it}\)

Threshold variable

\(\gamma\)

Threshold value to be estimated

\(e_{it}\)

Random disturbance item

\(\beta^{^{\prime}}_{1}\), \(\beta^{^{\prime}}_{2}\)

Coefficient to be estimated

\(\mu_{i}\)

Remove individual-specific means

\(I(.)\)

Indicator function