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Illinois Overview

Data Reporting Assessment (Learn more about data quality assessments)

Last updated

When Illinois reports no data, several days of data, or unusual data (such as decreases in values that should increase), our volunteers note it here on the date the anomaly occurred. We also note here changes in our own methodology that affect the data.

Negative test results reported in our API and CSVs are calculated by subtracting Total cases from Total PCR tests (specimens) in the absence of better data.

On March 4, 2021, we cleared the history of Negative (people or cases) in Illinois. This number mixed units and we no longer need it to calculate totalTestResults.

As of March 4, 2021, Illinois' totalTestResults is drawn from totalTestsViral instead of being calculated via positive+negative. This change had no impact on the number of tests at the topline.

On March 4, 2021, we backfilled the history of Illinois' Total PCR Tests (specimens) from data by date of report it posts on its website to add history from March 10, 2020 to May 24, 2020, when we did not have captured data.

On January 22, 2021, Illinois began including all probable deaths reported since the beginning of the pandemic in the total case count. This means all 1,903 Probable deaths were included in the cases reported on January 22, 2021.

On November 6, 2020, Illinois announced that they "will report confirmed cases and probable cases combined.” Due to this we cannot continue reporting Confirmed and Probable cases separately, however the time series for these metrics are available in the historical data, and our data downloads.

As of October 15, 2020, Illinois combines PCR and antigen tests in the total tests figure reported on the state's dashboard.

On September 4, 2020, Illinois reported over 140,000 new Total PCR tests (in specimens) and over 5,000 new Cases. According to the Chicago Tribune, "The Illinois Department of Public Health said Friday there was significant slowdown in the agency's test reporting earlier this week that it is just catching up with."