Table 7. Effect of Union Status on Log of Total Proposed Penalties per Mine-Quarter (Full Version: All Covariates)
Specification	Baseline (Hours Worked)	Employees	Tonnage
Union	0.228***	0.240**	0.184**	0.207**	0.135*	0.090
	(0.08)	(0.10)	(0.09)	(0.10)	(0.07)	(0.09)
Union X Mine Size	-0.113*	-0.170***	-0.119	-0.196***	-0.180	-0.242*
	(0.07)	(0.05)	(0.08)	(0.06)	(0.15)	(0.13)
Mine Size	0.301***	0.378***	0.326***	0.435***	0.495***	0.624***
	(0.05)	(0.06)	(0.07)	(0.07)	(0.12)	(0.16)
Log of Controller Size	0.111***	0.102***	0.134***	0.123***	0.123***	0.112***
	(0.01)	(0.02)	(0.02)	(0.02)	(0.01)	(0.02)
Lost-Day Injuries in Prev. Year	0.026***	0.029***	0.026***	0.029***	0.037***	0.041***
	(0.01)	(0.01)	(0.01)	(0.01)	(0.01)	(0.00)
Penalty Pts. in Prev. Year	0.065***	0.060***	0.066***	0.060***	0.075***	0.069***
	(0.01)	(0.01)	(0.01)	(0.01)	(0.01)	(0.01)
Mine Age	0.011***	0.012***	0.011***	0.012***	0.012***	0.012***
	(0.00)	(0.00)	(0.00)	(0.00)	(0.00)	(0.00)
Productivity	-0.014***	-0.014***	-0.017***	-0.017***	-0.032***	-0.034***
	(0.00)	(0.00)	(0.00)	(0.00)	(0.00)	(0.01)
NIOSH Longwall Dummy	0.143		0.134		0.277*
	(0.15)		(0.15)		(0.14)
Number of Coal Beds		-0.071		-0.078		-0.017
		(0.13)		(0.13)		(0.13)
Avg. Coal Bed Thickness (yds.)		0.014		0.008		0.025
		(0.05)		(0.05)		(0.05)
Subsidiary Indicator		0.130**		0.105*		0.151**
		(0.06)		(0.06)		(0.06)
Pct. Captive Production		-0.039		-0.040		-0.019
		(0.06)		(0.06)		(0.06)
Recoverable Reserves		-0.000***		-0.000**		-0.000*
		(0.00)		(0.00)		(0.00)
Pct. Continuous Mining Method		0.004***		0.005***		0.005***
		(0.00)		(0.00)		(0.00)
Pct. Conventional Mining Method		0.006***		0.006***		0.006***
		(0.00)		(0.00)		(0.00)
Pct. Longwall Mining Method		0.005**		0.005**		0.007***
		(0.00)		(0.00)		(0.00)
Pct. Shortwall Mining Method		0.012**		0.012**		0.013**
		(0.01)		(0.01)		(0.01)
Constant	8.331***	7.978***	7.120***	7.939***	7.709***	8.437***
	(0.19)	(0.24)	(0.20)	(0.24)	(0.23)	(0.27)
Subunit Dummies	Yes	Yes	Yes	Yes	Yes	Yes
Quarter Dummies	Yes	Yes	Yes	Yes	Yes	Yes
District Dummies	Yes	Yes	Yes	Yes	Yes	Yes
Observations	23,349	16,767	22,679	16,305	22,679	16,305
# of Union Mines / # of Total Mines	227 / 1,517	151 / 1,113	227 / 1,512	151 / 1,108	227 / 1,512	151 / 1,108
R2	0.53	0.56	0.54	0.56	0.53	0.55
Regression Date/Time	12/2/11 16:50	12/2/11 16:50	12/2/11 16:50	12/2/11 16:50	12/2/11 16:50	12/2/11 16:50

Table 7. Effect of Union Status on Log of Total Proposed Penalties per Mine-Quarter (Full Version: All Covariates)

Specification

Baseline (Hours Worked)

Employees

Tonnage

Model

Public Fields Only

Confidential Fields

Public Fields Only

Confidential Fields

Public Fields Only

Confidential Fields

Mine/Controller Size Units:

100 Quarterly FTEs

100 Employees

Millions of Tons

Union

0.228***

0.240**

0.184**

0.207**

0.135*

0.090

(0.08)

(0.10)

(0.09)

(0.10)

(0.07)

(0.09)

Union X Mine Size

-0.113*

-0.170***

-0.119

-0.196***

-0.180

-0.242*

(0.07)

(0.05)

(0.08)

(0.06)

(0.15)

(0.13)

Mine Size

0.301***

0.378***

0.326***

0.435***

0.495***

0.624***

(0.05)

(0.06)

(0.07)

(0.12)

(0.16)

Log of Controller Size

0.111***

0.102***

0.134***

0.123***

0.112***

(0.01)

(0.02)

(0.01)

(0.02)

Lost-Day Injuries in Prev. Year

0.026***

0.029***

0.026***

0.029***

0.037***

0.041***

(0.01)

(0.00)

Penalty Pts. in Prev. Year

0.065***

0.060***

0.066***

0.060***

0.075***

0.069***

(0.01)

Mine Age

0.011***

0.012***

0.011***

0.012***

(0.00)

Productivity

-0.014***

-0.017***

-0.032***

-0.034***

(0.00)

(0.01)

NIOSH Longwall Dummy

0.143

0.134

0.277*

(0.15)

(0.14)

Number of Coal Beds

-0.071

-0.078

-0.017

(0.13)

Avg. Coal Bed Thickness (yds.)

0.014

0.008

0.025

(0.05)

Subsidiary Indicator

0.130**

0.105*

0.151**

(0.06)

Pct. Captive Production

-0.039

-0.040

-0.019

(0.06)

Recoverable Reserves

-0.000***

-0.000**

-0.000*

(0.00)

Pct. Continuous Mining Method

0.004***

0.005***

(0.00)

Pct. Conventional Mining Method

0.006***

(0.00)

Pct. Longwall Mining Method

0.005**

0.007***

(0.00)

Pct. Shortwall Mining Method

0.012**

0.013**

(0.01)

Constant

8.331***

7.978***

7.120***

7.939***

7.709***

8.437***

(0.19)

(0.24)

(0.20)

(0.24)

(0.23)

(0.27)

Subunit Dummies

Yes

Quarter Dummies

Yes

District Dummies

Yes

Observations

23,349

16,767

22,679

16,305

22,679

16,305

# of Union Mines / # of Total Mines

227 / 1,517

151 / 1,113

227 / 1,512

151 / 1,108

227 / 1,512

151 / 1,108

0.53

0.56

0.54

0.56

0.53

0.55

Regression Date/Time

12/2/11 16:50

Definitions: Significance Levels: *** 1%, ** 5%, * 10%. FTE is defined as 2,000 man-hours.

Models: All models are ordinary least squares regressions; standard errors (shown in parentheses) are clustered at the mine level. The unit of analysis for all models is the mine-quarter.

Sample: public sample is: (1==1) (underground_mine==1) (coal_dummy==1) (bituminous==1) (active==1) (first_qtr_of_production==0) inrange(year, 1995, 2009). private sample is: (1==1) (underground_mine==1) (coal_dummy==1) (bituminous==1) (active==1) (first_qtr_of_production==0) inrange(year, 1998, 2009).

Independent Variables: All models include the following regressors: union dummy, union-size interaction term, mine size measure (defined as specified in column headers), logged controller size measure (defined as specified in column headers), mine age, productivity, number of lost-work injuries (in hundreds) in the previous four quarters, total penalty points (in thousands) in the previous four quarters, a constant term, dummies indicating presence of each type of mine subunit, quarter dummies, and district dummies. In addition: "Public Fields Only" models include the NIOSH longwall dummy; and "Confidential Fields" models include number of coal beds, mean coal bed thickness (in yards), subsidiary indicator, captive production as a percentage of total production, recoverable coal reserves, and mining method percentages.

Dependent Variable: the log of total proposed penalties per mine-quarter.