# A Tri-Model Prediction Approach for COVID-19 ICU Bed Occupancy: A Case Study
## 4 Results & Evaluation  
The trained forecasting algorithms get as input daily time series including COVID-19 cases, hospitalized, intubated, recovered, ICU patients and deaths. All results were collected to calculate new values, such as error rate to be used for further calculations. For evaluating model accuracy, the average of each metric for all algorithms was compared with actual values. The forecasting period expands from 23 November 2020 until 12 April 2021, utilizing data from 3 November 2020 until 23 March 2021. We focused on predicting hospitalized patients and more specifically ICU requirements. Confirmed cases may not represent the real number of infected people, as there is a limitation in the number of COVID-19 tests, but official numbers of ICU admissions is a solid data source. In order to evaluate the accuracy of each method, we used MAPE (Table 2), RMSE (Table 3), \(R^{2}\) (Table 4) and MAE (Table 5) for the predicted versus the actual values for this period, for four separate geographical regions of interest (Thessaloniki, Northern Greece, Attica and Greece) and for 1-3 weeks ahead. In these tables we also include the 3-day MA values per metric, providing a more reliable outlook on prediction error, given that the 3-day MA method unravels data collection lags attributed to weekends or national holidays. The first region in our report is the prefecture of Thessaloniki. For 1-week ahead predictions, from 23/11 until 22/3 the actual day and 3-day MA of all Models' Average for MAPE were 11.53% and 10.69%, for RMSE were 16.56 ICUs and 15.14 ICUs, for \(R^{2}\) were 93% and 94%, and for MAE were 12.13 ICUs and 11.04, respectively. Regarding the 2-weeks ahead prediction, from 7/12 until 22/3 the actual day and 3-day MA of all Models' Average for MAPE were 21.80% and 19.53%, for RMSE were 31.25 ICUs and 28.61 ICUs, for \(R^{2}\) were 85% and 88%, and for MAE were 24.05 ICUs and 22.24 ICUs, respectively. Finally, for the 3-weeks ahead prediction, from 21/12 until 22/3 the actual day and 3-day MA of all Models' Average for MAPE were 29.80% and 27.95%, for RMSE were 40.27 ICUs and 37.92 ICUs, for \(R^{2}\) were 63% and 68%, and for MAE were 31.33 ICUs and 29.77 ICUs, respectively. The second region is Northern Greece, including Thessaloniki along with Macedonia, Thrace, Epirus, and Thessaly. For 1-week ahead predictions, from 23/11 until 22/3 the actual day and 3-day MA of all Models' Average for MAPE were 10.88% and 9.12%, for RMSE were 46.26 ICUs and 43.57 ICUs, for \(R^{2}\) were 95% and 96%, and for MAE were 26.83 ICUs and 23.92 ICUs, respectively. Regarding the 2-weeks ahead prediction, from 7/12 until 22/3 the actual day and 3-day MA of all Models' Average for MAPE were 20.61% and 17.98%, for RMSE were 52.51 ICUs and 48.33 ICUs, for \(R^{2}\) were 84% and 87%, and for MAE were 42.96 ICUs and 39.38 ICUs, respectively. Finally, for the 3-weeks ahead prediction, from 21/12 until 22/3 the actual day and 3-day MA of all Models' Average for MAPE were 31.94% and 30.94%, for RMSE were 77.63 ICUs and 74.40 ICUs, for \(R^{2}\) were 63% and 66%, and for MAE were 63.37 ICUs and 60.86 ICUs, respectively. The third region is Greece, nationwide. For 1-week ahead predictions, from 1/2 until 22/3 the actual day and 3-day MA of all Models' Average for MAPE were 5.45% and 4.73%, for RMSE were 40.44 ICUs and 36.45 ICUs, for \(R^{2}\) were 94% and 95%, and for MAE were 29.89 ICUs and 27.10 ICUs, respectively. Regarding the 2-weeks ahead prediction, from 8/2 until 22/3 the actual day and 3-day MA of all Models' Average for MAPE were 11.40% and 10.24%, for RMSE were 78.5 ICUs and 73.38 UCUs, for \(R^{2}\) were 81% and 83%, and for MAE were 64.09 ICUs and 58.89 ICUs, respectively. Finally, for the 3-weeks ahead prediction, from 15/2 until 22/3 the actual day and 3-day MA of all Models' Average for MAPE were 18.81% and 17.86%, for RMSE were 126.05 ICUs and 121.32 ICUs, for \(R^{2}\) were 58% and 61%, and for MAE were 105.61 ICUs and 100.66 ICUs, respectively. The last region is the prefecture of Attica.