Correct FAQ entry for green/low risk encounters

Where to find the issue

German and English FAQ entry on green risk encounters.

Describe the issue

The current entry states: > All exposures for a diagnosis key that lasted less than 10 minutes in total (regardless of how close the smartphones came during that time) or during which the smartphones were more than 8 meters (73 dB attenuation) apart on average (regardless of how long the exposure lasted) are discarded as harmless. This is why the Corona-Warn-App can display encounters, but the risk status stays the same.

This suggests that encounters which are “discarded as harmless” are actually shown as green-/low-risk encounters, which is not correct.

Also: This suggests that only encounters shorter than 10 minutes would be discarded (which I guess corresponds to discarding encounters which only appeared in one listening window), when in reality encounters that are shorter than 15 min (i.e. up to and including 10 min (gt_5_le_10_min: 0) / two listening windows) are discarded.

Suggested change

1. Change the text so that it is clear that such encounters will be hidden from the user and not shown as green-/low-risk encounters. 2. Change the text regarding the time cutoff to state that encounters shorter than 15 min are discarded.

Edit: The 2nd point actually also applies to the risk-assessment documentation which is linked there and states: > All encounters for a diagnosis key that lasted less than 10 minutes in total […] are discarded as negligible risk.

This should also say “less than 15 minutes”.

Edit2: Regarding the change to “less than 15 minutes”: just make sure that I’m not talking nonsense here 😅 After looking at the config file again and seeing the eq_0_min entry (which seems to be pretty nonsensical if this would actually correspond to zero listening windows) I’m not entirely sure how the time mapping works, so just check with the ppl who know the details on how exactly this mapping works before changing anything.

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Edit3: ~~As @kbobrowski already stated below: it turns out that the FAQ entry seems to be correct after all: https://github.com/corona-warn-app/cwa-backlog/issues/23#issuecomment-679231707~~

I’d suggest putting this issue on hold until this has been clarified by the devs, just to be sure. If they confirm this, the issue can be closed. Although the question on how exactly the mapping/interaction between duration and exposure windows works would still be interesting 🙂.

Edit4: After https://github.com/corona-warn-app/cwa-website/pull/343 has been merged, the FAQ now actually contains a bug: the new formulation suggests that not all encounters would be shown in the app which is contradicted by @kbobrowski’s findings. I would suggest reverting #343 until this issue is sorted out to reduce the number of people receiving misinformation via the FAQ but in the meantime you can replace the enhancement label of this issue with the bug label again.

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Internal Tracking ID: EXPOSUREAPP-2344

[thomasaugsten]

Yes of course we will check this with apple to ensure we have a consistent API here.

[Ein-Tim]

Even if the FAQ entry is correct, I think it should be made clearer that all Encounters are shown to the user. In English it says:

"All exposures for a diagnosis key that lasted less than 10 minutes in total […] or during which the smartphones were more than 8 meters […] apart on average […] are discarded as harmless.

But then there is written:

This is why the Corona-Warn-App can display encounters, but the risk status stays the same.

In German the same:

Alle Begegnungen zu einer Positivkennung, die insgesamt weniger als 10 Minuten gedauert haben […] oder bei denen die Smartphones im Durchschnitt mehr als ca. 8 Meter Freiraum […] voneinander entfernt waren […], werden als unbedenklich verworfen. Deswegen kann die Corona-Warn-App Ihnen Begegnungen gemeldet haben, ohne dass die Risikobewertung sich ändert.

The word “discarded”(=“verworfen”) implicate that there are some Exposures who are discarded (=deleted, etc.). The user can misunderstand it and think not everything is shown to him/her. Better would be: “[…] are rated as harmless[…]” (“[…] als unbedenklich bewertet […]”)