This was a really interesting discussion and definitely a feature of many datasets that are often hidden by their reporting structures.
@kcharniga/@Gunnar/@amygimma/@medewitt/@rachaelpung or anyone else with good data access is the trend @adrianlison describes (of the proportion of cases with onsets etc decreasing over time regardless of when the nowcast is made) something you see in your data/experience?
As you suggest we can fudge this in the short-term by modelling a trend but in reality, extending the dimension of the data to have an additional definition of reporting seems like it will be needed to capture this well in data-rich settings (or to highlight the impact of lack of data richness to motivate better reporting systems).
Does anyone know if this has been discussed before in the literature? As far as I am aware it hasn’t been. As @adrianlison flags (and as flagged by @johannes here Create a collection of benchmark data sets) public access to some more real-world datasets (or synthetic versions that can be released) would greatly help to improve our ability to handle these kinds of issues.