New statewide testing metric and methodology updates announced

  • Sun Aug 30th, 2020 1:30am
  • News

Submitted by the Washington State Department of Health.

The Washington State Department of Health is making changes to the way we process and report testing data statewide, in an effort to account for the true volume of tests being done and to better benchmark our progress.

The following changes took effect on Aug. 25:

Total tests – The DOH data dashboard, and the risk assessment dashboard will now report on the total number of tests instead of the total individuals who were tested. This is a change from the old approach, which counted just one test per person, even if someone was tested more than once. With this new change, every test is counted, and the new data will improve our understanding of the testing situation as it now fully reflects the actual testing volume. This change was made to be more in line with other states’ methodologies as well as the Centers for Disease Control and Prevention.

Percent positive – The percent of total tests that are positive will also shift from being based on the percentage of unique individuals who test positive to the percentage of tests that are positive. While the data will change, and the DOH anticipates the percent positive will decrease somewhat because it is now accounting for total tests, the dashboard visualizations will stay the same.

Daily Testing Rate– The department of health will add this metric to the Risk Assessment dashboard. This additional measure helps the department to understand the per capita testing levels in the state and by county. The new measure allows easy comparisons of counties and other locations allowing us to better benchmark the state’s progress. It is calculated by dividing the average number of molecular tests performed over the past week by the population in the county or state and then multiplying by 100,000. The department of health will not be including any targets at this time, but that could change. This metric will replace the current, “Individuals tested per new case” on the risk assessment dashboard (which was an additional way of expressing the “percent positive” metric).