Subsample of Firms with One Industry Segment across Multiple Plants
| Dep. Var.: Log Avg. Wages | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| County | CZ | |||||||||
| SIC3 (1) | SIC3 (2) | SIC4 (3) | SIC4 (4) | SIC3 (5) | SIC3 (6) | SIC4 (7) | SIC4 (8) | |||
| log(HHI, ind–local–year) | -0.012 | -0.011 | -0.014 | -0.011 | -0.017 | -0.017 | -0.018 | -0.017 | ||
| -3.57 | -2.97 | -4.44 | -3.31 | -4.21 | -3.50 | -4.53 | -3.42 | |||
| log(emp, ind–local–year) | 0.028 | 0.029 | 0.028 | 0.031 | 0.026 | 0.027 | 0.027 | 0.029 | ||
| 22.28 | 19.50 | 22.32 | 19.70 | 19.15 | 16.08 | 19.16 | 16.78 | |||
| log(labor productivity) | 0.047 | 0.041 | 0.042 | 0.036 | 0.046 | 0.040 | 0.041 | 0.035 | ||
| 15.33 | 9.78 | 12.51 | 7.71 | 13.10 | 8.56 | 11.19 | 7.25 | |||
| log(plants per segment) | 0.002 | 0.006 | 0.001 | 0.004 | ||||||
| 0.32 | 0.78 | 0.08 | 0.48 | |||||||
| log(plants per firm) | -0.013 | -0.014 | -0.012 | -0.012 | ||||||
| -1.88 | -1.94 | -1.66 | -1.72 | |||||||
| Plant age (/100) | 0.359 | 0.371 | 0.362 | 0.373 | 0.373 | 0.384 | 0.378 | 0.390 | ||
| 29.30 | 25.20 | 27.53 | 23.77 | 29.02 | 24.76 | 27.28 | 23.23 | |||
| Year fixed effects | Y | Y | Y | Y | ||||||
| Industry fixed effects | Y | Y | Y | Y | ||||||
| Industry–year fixed effects | Y | Y | Y | Y | ||||||
| Firm fixed effects | Y | Y | Y | Y | ||||||
| Firm-year fixed effects | Y | Y | Y | Y | ||||||
| Observations | 226,000 | 226,000 | 187,000 | 187,000 | 226,000 | 226,000 | 187,000 | 187,000 | ||
| R2 | 0.6348 | 0.7423 | 0.6463 | 0.7523 | 0.6352 | 0.7430 | 0.6469 | 0.7531 | ||
Notes: This table examines the effects of employer concentration in a local labor market on the wages of plants using a subsample of plants owned by firms that have multiple plants in only one industry segment. 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. Columns 1–4 (Columns 5–8) present estimates using counties (CZs) to define local labor markets. Columns 1–2 and 5–6 (Columns 3–4 and 7–8) present estimates using three- and four-digit SIC industries to compute HHI, log(employment), and log(plants per segment). 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.