Per some comments in a thread on mediawiki.org, there is a suspicion that the deployment of the collapsed language links has decreased the page views to the Ukrainian Wikipedia as a result of some users browsers being configured to Russian, thereby burying the link to the Ukrainian Wikipedia. Our previous analysis suggests that this suspicion is incorrect, and the page views dashboard also does not seem to indicate there has been a drop, but we should confirm whether this is really the case using statistical analysis.
Hypothesis: deployment of collapsed links to wikipedia.org has significantly decrease page views to https://uk.wikipedia.org. Let's perform whatever analysis we need to to decide whether to reject or accept this hypothesis.
Note: We recently released this new dashboard page to view any changes in the language clickthroughs from the Wikipedia.org portal page (ticket T140816)