Our data source for test data, the Covid Tracking Project, changed its definition of the contents of its totalTestResults field for Florida. We use this data for our positivity calculation denominator. This will will likely reduce the state's positivity percentage because people are deduplicated people less frequently, resulting in a bigger denominator.
Previously, the totalTestResults field included Positive Cases + Negative Test Results. Now, the field includes Test Encounters, which are defined as the total number of people tested per day via PCR testing. The count for this metric is incremented up by one for each day on which an individual person is tested, no matter how many specimens are collected from that person on that day. If an individual person is tested twice a day on three different days, this count will increment up by three.
Data Sources: Cases and deaths data from JHU CSSE. As of August 1, 2020, policy events are drawn from from various state-specific sources. Prior to that, the data source for policy events was the National Governor’s Association.
Our data provider, The Covid Tracking Project, is in the process of changing how it maps states’ data to the categories we use for our positivity calculations. These changes mean the category of data we use in our denominator (Total tests) may now include tests previously not included in our calculations, which in turn may result in a test positivity calculation that is lower than what we would have calculated for the state prior to the change.
With this significant change, we will once again review our data inputs and calculations to ensure that our numbers reflect the most responsible public health calculation of test positivity.