Changes in data presentation for test activity in Norway
To date we have only presented the number of new people tested, that is those who have been tested for the first time. People who have been tested more than once have therefore not been included in the statistics more than once. There can be several reasons why someone is tested more than once. Some are tested several times for the same incident (either because of illness or as part of contact tracing). Some are retested because of new incidents, such as newly arisen respiratory tract symptoms. In practice, this means that there has been a higher test activity than shown in the statistics so far. The NIPH has been working to improve the presentation of test data to better reflect current test activity.
The difference is illustrated in this figure:
In the weekly report for week 41, we distinguish between
- Number of tests: Total number of tests performed, regardless of whether the same person is tested several times
- Number of first-time testers: A person is only included once. In the case of a positive test result, the first positive test will be counted in the statistics
- Number of persons tested: a new test on a person is defined as a test performed at least 7 days after the previous test on the same person. If the person is retested after 7 days, the person is counted again.
This is to avoid counting several tests for the same disease incident, but allowing the person to be included in the statistics when tested for new disease incidents.
This means that the supporting data for the number of people tested has now been changed and means that a person can be included in the statistics several times.
It will still take some time before the statistics on the number of people tested in our daily visualisation solution are updated to the new definition. This means that there may be temporary inconsistencies in data from the various information sources.