ARIMA specifications and covariate effects on the number of ED visits between 1 January 2014 and 31 December 2018 (training sets)
| | Hospitals | |||||
| A | B | C | D | E | ||
| Model specification | ARIMA parameters (p, d and q) | (0, 1, 2) | (1, 1, 1) | (1, 1, 2) | (1, 1, 1) | (1, 1, 1) |
| Fourier terms* | 3, 13 | 3, 14 | 3, 13 | 3, 16 | 3, 15 | |
| Covariate effects (SE)† | Temperature (°C) | 1.29 (0.15) | 1.23 (0.14) | 0.68 (0.11) | 1.16 (0.18) | 1.84 (0.18) |
| Humidity (%) | −0.08 (0.04) | |||||
| Precipitation (mm) | −0.2 (0.05) | −0.12 (0.05) | −0.13 (0.07) | −0.31 (0.06) | ||
| NO2 (μg/m3) | −0.08 (0.03) | −0.09 (0.04) | ||||
| PM10 (μg/m3) | 0.03 (0.02) | |||||
| ILI (weekly new cases per 1000 inhabitants) | 1.74 (0.41) | 1.05 (0.37) | 0.73 (0.29) | 0.97 (0.46) | ||
| Festivity | −28.23 (1.98) | −12.96 (1.45) | −25.42 (2.23) | −14.56 (2.39) | ||
| Special festivity‡ | −43.16 (6.31) | −57.64 (6.36), −62.61 (6.29) | −42.06 (4.92) | −59.86 (7.58) | −63.24 (7.92) | |
| Day before/after festivity | 7.14 (1.5) | 9.06 (1.58) | 3.75 (1.22) | 13.89 (1.96) | ||
*Number of sine and cosine terms used to approximate day of the week and year-round seasonality.
†Parameter estimates and SEs in parentheses. Predictors were retained in the final model only if statistically significant (p value <0.05).
‡New Year’s Eve for hospitals A, C and D, and New Year’s Eve and 15 August for hospital B.
.ARIMA, autoregressive integrated moving average; ILI, influenza-like illness; NO2, nitric oxide; PM10, particulate matter with a diameter of ≤10 µm.