On March 30, 2020, Wisconsin revised its cumulative Negative PCR tests (people) data downward without explanation.
In early June of 2020, Wisconsin started reporting probable cases of COVID-19 separately from confirmed cases of COVID-19. On June 25, 2020, The COVID Tracking Project added more than two weeks' worth of probable cases to our Cases (confirmed plus probable) for WI, initially causing a large single day increase in cases. We subsequently updated our historical Cases data using data provided to us by the state, which eliminated this one-day increase.
In early June of 2020, Wisconsin started reporting probable deaths from COVID-19 separately from confirmed deaths from COVID-19. We did not discover this data until June 29, 2020, and so our time series only has data for this metric beginning on that date.