Sensitivity analyses
In sensitivity analyses, we found using absence duration did not improve model predictions. One-day absence models and those including both one-day and absences two-days or more had lower relMAEs compared to models containing absences two-days or more (Supplemental Table 9), but predictions from the three model did not substantially vary (Supplemental Figure 2). Evaluation of models including one-week lagged influenza cases found little improvement of model prediction and performance when compared to seasonal models. Higher MAEs were observed for one-week lagged influenza models, and one-week lagged influenza and absence models but had similar R2 estimates (Supplemental Table 8). One exception was the one-week lagged influenza model from the leave 20% schools’ out validation, which had a lower relMAE (relMAE: 0.97) (Supplemental Table 8). One-week lagged influenza and one-week lagged influenza and kindergarten absence models performed similarly to one-week lagged influenza models in three cross-validations, except in the leave 52-weeks out validation (relMAE: 0.97).