[discovery] Results of Language Switching A/B Test

Hey all,

I'm pleased to share the results of our language switching A/B test. This was an experiment to see if language detection on failed queries - and then rerunning in the "appropriate" language - could produce a better outcome for users.

The long and the short of it is that it does produce a marginally better outcome for web users, but not for API users. Our recommendation is to enable it as the default user experience for web users but NOT API users, if that is possible, and disable the test if not.

You can see the full report at https://github.com/wikimedia-research/LangTest/blob/master/report.pdf

Thanks!