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Table 2.

Unit root tests.

Level
First difference
ADFPPADFPP
BOD −2.854800 −2.802497 −5.996425** −7.272027** 
Inequality (Theil) −2.091449 −2.140890 −4.207627** −5.116411** 
Inequality (Gini) −1.669229 −1.082935 −3.751055** −3.140159 
Income −1.647986 −1.562229 −6.270841** −7.832962** 
Level
First difference
ADFPPADFPP
BOD −2.854800 −2.802497 −5.996425** −7.272027** 
Inequality (Theil) −2.091449 −2.140890 −4.207627** −5.116411** 
Inequality (Gini) −1.669229 −1.082935 −3.751055** −3.140159 
Income −1.647986 −1.562229 −6.270841** −7.832962** 

Note: All estimates include constant and trend. The Schwarz criterion is used to determine the optimal number of lags in the ADF test. The Newey-West method and the Bartlett kernel are used for the bandwidth in the PP test.

**Significance at the 5% level.

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