@vaughnwalters For the first message/scenario we agreed to show that message rather than not showing the tab at all here T341341, though I can't find the reason for that. Perhaps @Daimona knows.
I don't think we should change it unless we know the reason for the previous decision.

For the 2nd scenario i think we can use the same message:
"This event has no responses from participants to aggregate"

In T363211#9739880, @gonyeahialam wrote:

@vaughnwalters For the first message/scenario we agreed to show that message rather than not showing the tab at all here T341341, though I can't find the reason for that. Perhaps @Daimona knows.

I think we did that for better discoverability of the stats tab, but I'm not 100% sure. However, we didn't consider the scenario of an event not having any questions enabled, because at the time every event would have all questions enabled; it was just for the case of there not being any answers.

Eng - Design Meeting
For the first scenario, where no questions are enabled by the organizer from the start we can decide not to show the Response statistics tab

In T363211#9740740, @gonyeahialam wrote:

Eng - Design Meeting
For the first scenario, where no questions are enabled by the organizer from the start we can decide not to show the Response statistics tab

Same for when the questions were added and then removed

Given an event has ended and the final aggregation has occurred
When there are no participant questions enabled, but the participant questions were previously enabled and participants recorded their answers but then the organizer removed all participant questions, the Response statistics tab displays the following message: Participants' responses will be aggregated and made available here shortly. This is inaccurate as the final aggregation has already occurred and there are no questions enabled to be aggregated ( though there were questions enabled and answered previously ).

I cannot reproduce this. I do get this behaviour, but only before the "final aggregation" has run. Once that happens (and the redundant answers get deleted), I get the same message as the scenario #1.

Still, that doesn't change the AC -- the tab shouldn't be shown at all.

Change #1023887 had a related patch set uploaded (by Daimona Eaytoy; author: Daimona Eaytoy):

[mediawiki/extensions/CampaignEvents@master] SpecialEventDetails: do not show stats tab if no questions are enabled

https://gerrit.wikimedia.org/r/1023887

Change #1023887 merged by jenkins-bot:

[mediawiki/extensions/CampaignEvents@master] SpecialEventDetails: do not show stats tab if no questions are enabled

https://gerrit.wikimedia.org/r/1023887