== Background
Prior to deployment, we would like to complete the analysis of the page previews a/b test for page previews.
== Acceptance criteria
- Repeat the analysis from {T139319}/{T145770} for the two A/B tests on enwiki and dewiki (from October/November 2017 and December 2017-February 2018)
- Report feature performance cumulative and per-wiki:
-- Difference in pageviews per session --> T182314#3974663
-- Difference in page interactions (pageviews + previews) per session --> T182314#4016412
-- Average cards viewed per page --> T182314#3901330
-- Average cards viewed per session --> T182314#3901330
-- Average number of disctinct pages interacted with per session --> T182314#4025928
-- Disable rates --> T182314#3909766 (first test), T182314#3909766 (second test)
-- Usage of back button --> T144603#4010992
-- Nice to have: Effects on "reading depth" (i.e time spent per page, from [[https://meta.wikimedia.org/wiki/Schema:ReadingDepth|the ReadingDepth schema]])