Cumulative Cases by Specimen Date

What does the Public Health England data table show?

In the Public Health England dashboard, there is a table of confirmed cases by specimen date. Journalist Robert Peston (ITV) sounded on Twitter:

As you can see it makes no sense at all. There is weird repetition and none of the columns reconcile.

This article aims to make sense of what the data table shows.

Thinking about cumulative cases