Table 11—
Robustness of Mortality and Life-Years Lost IV Estimates to Including Fewer or More Instrument Lags
| No lags | 1 lag | 3 lags | 4 lags | 5 lags | |
|---|---|---|---|---|---|
| (1) | (2) | (3) | (4) | (5) | |
| Panel A. Mortality | |||||
| PM 2.5 (μg/m3) | 0.602 | 0.730 | 0.687 | 0.683 | 0.680 |
| (0.077) | (0.061) | (0.061) | (0.061) | (0.061) | |
| F-statistic | 389 | 304 | 298 | 298 | 297 |
| Dependent variable mean | 385 | 385 | 385 | 385 | 385 |
| Observations | 1,980,549 | 1,980,549 | 1,977,622 | 1,974,768 | 1,971,974 |
| Panel B. Life-years lost | |||||
| PM 2.5 (μg/m3) | 2.737 | 3.267 | 2.997 | 2.993 | 2.978 |
| (0.488) | (0.477) | (0.487) | (0.485) | (0.480) | |
| F-statistic | 392 | 310 | 304 | 304 | 303 |
| Dependent variable mean | 2,224 | 2,224 | 2,224 | 2,224 | 2,224 |
| Observations | 1,898,236 | 1,898,236 | 1,895,565 | 1,892,953 | 1,890,387 |
Notes: Table reports IV estimates of equation (1) from the main text. Column headings report the number of instrument lags included in the regression. (The specification reported in other tables includes two lags.) Dependent variable in panel A is the three-day mortality rate per million beneficiaries. Dependent variable in panel B is the life-years lost over three days per million continuously enrolled fee-for-service (FFS) beneficiaries. Estimates are weighted by the number of Medicare beneficiaries in panel A and by the number of FFS beneficiaries in panel B. Standard errors, clustered by county, are reported in parentheses.