Hello!
As part of our goal to reduce the zero results rate https://www.mediawiki.org/wiki/Wikimedia_Engineering/2015-16_Q1_Goals#Search, the Discovery Department is currently running an A/B test to try different parameters for the search suggester. We're hoping that our new parameters will give users more suggestions without decreasing their quality.
The reason we've chosen to tweak the suggestions is because of our recent work https://phabricator.wikimedia.org/T105202 to automatically run queries for the user if they get zero results but have a suggestion. The purpose of this A/B test is to determine whether this has significant impact towards achieving our goal or not.
This is the first A/B test that the Discovery Department has run, so we're still ironing out the process. We hope to run many more A/B tests in the future.
For further information on this, please review the associated Phabricator task https://phabricator.wikimedia.org/T108103.
If you have any questions, I'd be happy to answer them.
Thanks, Dan