CirrusSearch collects data on 1 in 200 search sessions, sometimes that is increased to say 1:100 and the extra users are split into buckets as part of the AB test using this javascript:

On Thu, Sep 8, 2016 at 11:26 AM, James Forrester <> wrote:
On Wed, 7 Sep 2016 at 00:16 Jan Dittrich <> wrote:
Hello Analytics,

A while ago I asked about the existence of any A/B-Testing Framework. I got to know (Thanks, Nuria!) that is in preparation. However, I assume, that until this is in place, we need to use custom solutions which utilize EventLogging.
Event logging itself is pretty clear to me, but not the splitting/cookie logic.

Could anybody link me some examples for such a self implemented way to show users their assigned content and, if they are not assigned to a group yet, to assign users to A/B… bins?

Here's the code for MW-VE to add a proportion of new accounts to have VE on by default, used when slowly ramping up deployment or for an A/B test:;7fe96fc2380743b4e63f4bb7c03e2ebf2b2e1038$964 — hope that helps.

James D. Forrester
Lead Product Manager, Editing
Wikimedia Foundation, Inc.

jforrester at | @jdforrester

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