Hi,
as most on this list will be aware, on the mobile web version of Wikipedia, all top-level sections below the lead section are currently shown collapsed on initial view. Users can tap on a section heading to show the content, and to collapse it again. To examine the tradeoffs of this solution and inform future product decisions, we ran an experiment where 0.05% of mobile web users were shown all pages with every section expanded on initial load, instrumented alongside a control group of 0.05% that kept seeing the standard view where all sections all initially collapsed.
A high-level summary of results is now available at https://meta.wikimedia.org/wiki/Research:Collapsed_vs_uncollapsed_section_vi... . In particular:
* Readers in the test group (sections expanded) tend to stay longer on the page * Readers in the test group tend to spend more time reading, and less time navigating * Readers in the test group tend to scroll more sections into view than readers in the control group open * Readers in the test group tend to stay shorter on the page than readers using the Android Wikipedia app (which offers a TOC for easier navigation, something not yet available in the mobile web test group)
Comments and questions are welcome, feel free to use the talk page for them too.
Note that this experiment only measured some aspects, and that the results don't yet allow the unambiguous conclusion that it would be better to switch to the uncollapsed view. That said, they certainly suggest that such a change should be considered. It is being planned to examine this question further with some user testing sessions.
(As an experiment, I've taken the opportunity to write this up this analysis as a page in the research namespace on Meta, instead of on Phabricator or in form of an email as done on other occasions. Feedback on the format is welcome too.)