Given the high abandonment rates of the welcome survey in Vietnamese Wikipedia (see T216668), we may want to change the experiment running in that wiki from the current state (half of newcomers get Var A and half get Var C) to a new state (half of newcomers get Var A and half get control).
We thought we had enough evidence from Czech and Korean Wikipedias that the surveys did not cause abandonment problems that all that was left to do was decide which survey variant to use going forward. Since the abandonment rate on desktop in Vietnamese Wikipedia is 46%, we now may want to compare that against a control group to see if the survey is causing it.
And the reason that the new experiment would be Var A vs Control instead of Var C vs Control is that we have seen that Var A outperforms Var C on every metric in all wikis and on both platforms.
We will do this task depending on whether the Vietnamese community has insight into this issue (T216668), which we hope to gain during the next week.