Table 2.
Poisson regression results using quartile categories of explanatory variables.
| Variable name | unit | Exp (coefficient of explanatory variable) | P-value of Wald test (P-value for trend) | Residual Deviance | AIC | ||
|---|---|---|---|---|---|---|---|
| estimate | 95% CI | ||||||
| Proportion of estimated external radiation does ≥ 1 mSv | proportion among surveyed people | Q1 | Reference | (0.757) | 46.554 | 132.62 | |
| Q2 | 1.169 | (0.584, 2.340) | 0.659 | ||||
| Q3 | 1.059 | (0.508, 2.211) | 0.878 | ||||
| Q4 | 1.149 | (0.602, 2.196) | 0.673 | ||||
| Distance from the FNPP | 1 km | Q1 | Reference | (0.370) | 45.924 | 131.99 | |
| Q2 | 0.958 | (0.631, 1.454) | 0.840 | ||||
| Q3 | 0.945 | (0.537, 1.664) | 0.845 | ||||
| Q4 | 0.622 | (0.221, 1.747) | 0.368 | ||||
| Altitude | 100 m | Q1 | Reference | (0.623) | 43.624 | 129.69 | |
| Q2 | 1.439 | (0.964, 2.149) | 0.075 | ||||
| Q3 | 1.183 | (0.612, 2.286) | 0.618 | ||||
| Q4 | 1.299 | (0.612, 2.756) | 0.495 | ||||
| Population density | 1000 persons per square kilometre | Q1 | Reference | (0.560) | 45.536 | 131.60 | |
| Q2 | 1.159 | (0.257, 5.227) | 0.848 | ||||
| Q3 | 1.653 | (0.390, 7.011) | 0.495 | ||||
| Q4 | 1.357 | (0.333, 5.520) | 0.670 | ||||
| Proportion of workers in agriculture, forestry, and fisheries industry | proportion among workers | Q1 | Reference | (0.970) | 44.080 | 130.14 | |
| Q2 | 0.889 | (0.546, 1.448) | 0.638 | ||||
| Q3 | 0.547 | (0.239, 1.252) | 0.153 | ||||
| Q4 | 1.198 | (0.486, 2.953) | 0.695 | ||||
| Unemployment | proportion among labour force | Q1 | Reference | (0.371) | 43.628 | 129.69 | |
| Q2 | 0.944 | (0.328, 2.722) | 0.916 | ||||
| Q3 | 1.351 | (0.488, 3.745) | 0.562 | ||||
| Q4 | 1.428 | (0.510, 4.001) | 0.498 | ||||
| Proportion of professional and technical workers | proportion among workers | Q1 | Reference | (0.995) | 45.785 | 131.85 | |
| Q2 | 1.239 | (0.346, 4.441) | 0.742 | ||||
| Q3 | 0.880 | (0.256, 3.021) | 0.839 | ||||
| Q4 | 1.125 | (0.356, 3.559) | 0.841 | ||||
Each estimation result of Poisson regression model using quartile categories (Q1, Q2, Q3, and Q4) of one explanatory variable (shown in the 1st column) consists of four rows to report the estimated coefficients of the four quartile categories. For each model, the lowest quartile (Q1) is set as the reference category. Estimates of intercept terms were omitted. n = 59 (municipalities) for all of the models.
A small Wald test p-value indicates that the coefficient is considerably different from that of the reference category. AIC, Akaike information criterion; FNPP, Fukushima Daiichi Nuclear Power Plant; N/A, not applicable; CI, confidence interval.