Cwa-documentation: Reliability & Delay: from test result to CWA-backend

[mrlnc]

Issue #400 indicates that some test results never appear in CWA due to issues in the exchange lab -> CWA-backend.

Is there public monitoring and documentation on the reliability of the lab -> CWA-backend exchange?

For example,

• how many test results are available at laboratories but never entered into the CWA backend?
• what is the estimated delay from test result to CWA backend?
• how many users think they will get the test result in CWA (scanned the code) but never receive one?

QR-codes that have been scanned (polling the server) but don't receive results after X days could provide an upper bound. Further, they could give insights into the maximum delay (patient scans the code no earlier than arriving at the test center).

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Internal Tracking ID: EXPOSUREAPP-5774

[mrlnc]

https://github.com/corona-warn-app/cwa-app-android/issues/1084
If I understand this issue correctly, tests expire within 21 days after registration. Smartphones would then stop polling for test results, leaving less smartphones with invalid tests polling the servers forever.

[mrlnc]

Available Data

Date of User scanning the QR code:
AppSession->createdON in Verification Server. More precise, this the time that users agree to receive results through the app, and their app successfully registers the registration token.
https://github.com/corona-warn-app/cwa-verification-server/blob/master/docs/architecture-overview.md#entity-appsession

Date of Laboratory providing the Results:
TestResult->result_date in Testresult Server. This is the time a new test result is registered in the Testresult Server.
https://github.com/corona-warn-app/cwa-testresult-server/blob/master/docs/architecture-overview.md#entity-test-results

Both entries are associated with the test result's GUID (resp. its hash).

Analysis

Users assume that the test result will be delivered through the app, if they successfully register test using the QR code. #400 indicates that sometimes, the test results never make it to the app.

Users never receiving test results through the app

• for all AppSessions with createdOn older than 21 days, how many are missing a corresponding test result?
  (test results expire after 21 days, hence, should always arrive before)

Test result delivery delay

• for all test results with corresponding AppSessions, what is the timespan between TestResult->result_date and AppSessions->createdOn?

[mrlnc]

for reference, the method proposed here would help quantify the following FAQ:
https://www.coronawarn.app/de/blog/2020-08-25-notes-qr-codes/

[mrlnc]

By now, are there any figures how many users actually get results after registering the test in the app?

[Ein-Tim]

Maybe this comment helps: https://github.com/corona-warn-app/cwa-documentation/issues/475#issuecomment-747517091

[mrlnc]

@heinezen @alanrick bezüglich https://github.com/corona-warn-app/cwa-documentation/issues/475#issuecomment-747517091: wird im Backend erfasst, wieviele Nutzer zwar auf ein Testergebnis warten, aber kein Ergebnis übermittelt bekommen (z.B. weil die Checkbox fehlt?)

Wäre aus meiner Sicht möglich, indem die hier beschriebenen Werte verglichen werden

[alanrick]

@mrlnc You have a better understanding of it than I do. But I don’t disagree. In addition you might be able to determine an _indication_ of

Process Compliance

for all TestResults older than, say, 5 days, how many are missing a corresponding AppSession (SourceOfTrust is “hashedGUID”)?

I.e Lab has fed test results into the Test Server, but the patient hasn’t scanned the qrcode with the CWA (and synced within 5 days).