Employer Concentration and Wages by Ten-Year Time Period
| Dep. Var.: Log Avg. Wages | |||||
|---|---|---|---|---|---|
| 1978–1987 (1) | 1988–1997 (2) | 1998–2007 (3) | 2008–2016 (4) | 2008–2010 (5) | |
| Panel A: Counties as Local Areas | |||||
| log(HHI, SIC3–county–year) | 0.000 | -0.009 | -0.015 | -0.020 | -0.020 |
| -0.11 | -2.58 | -4.30 | -7.53 | -6.26 | |
| log(emp, SIC3–county–year) | 0.041 | 0.037 | 0.026 | 0.018 | 0.019 |
| 30.66 | 28.21 | 19.45 | 15.12 | 12.06 | |
| log(labor productivity) | 0.100 | 0.073 | 0.051 | 0.050 | 0.050 |
| 40.21 | 32.52 | 27.18 | 27.26 | 21.12 | |
| log(plants per segment) | -0.002 | -0.012 | -0.010 | -0.008 | -0.008 |
| -1.45 | -5.43 | -5.11 | -3.64 | -2.65 | |
| log(plants per firm) | -0.002 | -0.003 | -0.006 | 0.000 | -0.017 |
| -1.26 | -1.55 | -2.40 | 0.00 | -2.05 | |
| Plant age (/100) | 0.743 | 0.461 | 0.294 | 0.180 | 0.197 |
| 18.66 | 22.66 | 24.19 | 20.37 | 16.71 | |
| Year fixed effects | Y | Y | Y | Y | Y |
| Industry fixed effects | Y | Y | Y | Y | Y |
| Firm fixed effects | Y | Y | Y | Y | Y |
| Observations | 248,000 | 250,000 | 238,000 | 209,000 | 69,000 |
| R2 | 0.6536 | 0.6181 | 0.5362 | 0.5785 | 0.6054 |
| Panel B: Commuting Zones as Local Areas | |||||
| log(HHI, SIC3–CZ–year) | -0.001 | -0.011 | -0.014 | -0.018 | -0.018 |
| -0.48 | -3.41 | -3.48 | -5.85 | -5.46 | |
| log(employment, SIC3–CZ–year) | 0.038 | 0.035 | 0.028 | 0.020 | 0.022 |
| 31.11 | 23.31 | 20.09 | 14.22 | 12.62 | |
| log(labor productivity) | 0.098 | 0.072 | 0.050 | 0.049 | 0.050 |
| 33.67 | 28.16 | 24.29 | 25.58 | 20.89 | |
| log(plants per segment) | -0.002 | -0.005 | -0.007 | 0.000 | -0.018 |
| -1.20 | -2.12 | -2.54 | -0.10 | -2.06 | |
| log(plants per firm) | -0.002 | -0.011 | -0.009 | -0.008 | -0.008 |
| -0.92 | -5.11 | -4.88 | -3.71 | -2.66 | |
| Plant age (/100) | 0.815 | 0.490 | 0.306 | 0.186 | 0.204 |
| 19.69 | 22.58 | 25.12 | 20.77 | 16.38 | |
| Year fixed effects | Y | Y | Y | Y | Y |
| Industry fixed effects | Y | Y | Y | Y | Y |
| Firm fixed effects | Y | Y | Y | Y | Y |
| Observations | 248,000 | 250,000 | 238,000 | 209,000 | 69,000 |
| R2 | 0.6515 | 0.6186 | 0.538 | 0.5804 | 0.6076 |
Notes: This table examines the basic effects of employer concentration in a local labor market on the wages of plants by ten-year period for 1978–2016. The dependent variable is the log of average wages per worker as defined in Table 1. log(HHI) and log(employment) are lagged by one year. The table presents estimates using three-digit SIC industries to compute HHI, log(employment), and log(plants per segment). Panels A and B present estimates using counties and CZs to compute HHI and log(employment). The t-statistics based on standard errors adjusted for sample clustering at the county or CZ level are reported below the coefficient estimates. The numbers of observations are rounded to the nearest thousand to follow the U.S. Census Bureau’s disclosure rules.