Performance of nowcasts of Nt on incomplete line list data of a simulated first wave scenario using different approaches to account for missing onset dates.

Shown is the performance of Nt nowcasts in four different phases of the epidemic wave, at different lags of a selected week (same week [0–6 days], one week after [7–13 days], and two weeks after [14–20 days]). Nowcasts were obtained through i) a stepwise approach using an independent imputation step, ii) a stepwise approach using a backward imputation step, and iii) a generative approach using an integrated missingness model. Performance is measured by the weighted interval score (WIS, lower is better), shown is the average score over 50 scenario runs () and the percentage of runs in which each approach achieved the best score (%best).