Table 2. Pooled and random-effect regressions.
| Disease/Pollutant | Pooled OLS | Random effects | LM test | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Coefficients | Robust SE | N | R2 | Coefficients | Robust SE | N | R2 | ||
| Respiratory diseases | |||||||||
| PM10 | 0.1123 * | 0.0374 | 615 | 0.683 | 0.092 * | 0.024 | 615 | Within = 0.132 | Probability > χ2 = 0.000 |
| Between = 0.774 | |||||||||
| Overall = 0.663 | |||||||||
| PM2.5 | 0.1524 | 0.093 | 191 | 0.678 | 0.066 | 0.038 | 191 | Within = 0.329 | Probability > χ2 = 0.000 |
| Between = 0.734 | |||||||||
| Overall = 0.648 | |||||||||
| Stroke | |||||||||
| PM10 | 0.208 * | 0.0422 | 615 | 0.471 | 0.145 * | 0.042 | 615 | Within = 0.413 | Probability > χ2 = 0.000 |
| Between = 0.003 | |||||||||
| Overall = 0.044 | |||||||||
| PM2.5 | 0.1731 * | 0.0572 | 191 | 0.689 | 0.024 | 0.049 | 191 | Within = 0.016 | Probability > χ2 = 0.000 |
| Between = 0.389 | |||||||||
| Overall = 0.473 | |||||||||
| Diabetes | |||||||||
| PM10 | 0.0332 * | 0.0122 | 615 | 0.269 | -0.01 | 0.013 | 615 | Within = 0.025 | Probability > χ2 = 0.000 |
| Between = 0.27 | |||||||||
| Overall = 0.216 | |||||||||
| PM2.5 | -0.081 | 0.0595 | 191 | 0.16 | -0.002 | 0.036 | 191 | Within = 0.013 | Probability > χ2 = 0.000 |
| Between = 0.161 | |||||||||
| Overall = 0.095 | |||||||||
| Cancer | |||||||||
| PM10 | -0.0021 | 0.0197 | 615 | 0.481 | -0.01 | 0.007 | 615 | Within = 0.237 | Probability > χ2 = 0.000 |
| Between = 0.516 | |||||||||
| Overall = 0.47 | |||||||||
| PM2.5 | 0.0303 | 0.0218 | 191 | 0.688 | -0.001 | 0.016 | 191 | Within = 0.261 | Probability > χ2 = 0.000 |
| Between = 0.722 | |||||||||
| Overall = 0.667 | |||||||||
GDP: gross domestic product; LM: Breusch-Pagan Lagrange multiplier test; OLS: ordinary least squares; PM: particulate matter; SE: standard error.
Notes: models include as control variables the logarithm of annual GDP per capita, the average age of population, the number of physicians per 1,000 inhabitants, and a time trend as a dummy variable. PM concentrations are expressed as logarithms.
* Indicates significance at a 1% level.