Hello everyone, I recently started a 50/50 experiment on my e-commerce site. I can't figure out why I'm not getting a 50/50 split in my experiment. What are the usual reasons for this kind of behavior ? Thx for you help !

There could be a few different reasons. First, how long has the test been running? Do you get any warnings on the Health tab? Finally, what kind of test is it (feature flag/visual/redirect)?

Since 3 weeks It's a feature flag

This looks like there's something up with the implementation (feature flag in code) that's causing the experiment exposure to be logged incorrectly. Can you share your flag setup?

You mean the way we call growthbook or the setup of my flag inside growthbook ?

I mean how you set it up in your codebase. Are you able to share your code snippets where you set up GrowthBook and make your experiment exposures?

yes let me know if this is enought for you

There are two things that could be causing issues: 1. The "anonymous" user id. Whenever a user doesn't have a google analytics id, then they'll use anonymous as their user id, meaning that they will all get the same variation. If a large portion of your users don't have this cookie, then that'll definitely be the cause of your issue. To remedy, you should assign them a random ID. We also have a tracking plugin you can use with the SDK that may help. 2. The

loadFeatures()

method is deprecated in favor of

await growthbook.init()

. I'm not sure this is contributing to the issue, but I think there could be some timing issues with your setup. We do have a guide on Vue here: https://docs.growthbook.io/lib/vue

Thx for you answer ! Given the difference in volume between 5,000 and 3,000, this would mean that around 20% of my traffic does not have a Google Analytics ID. Does this ratio seem consistent to you? How can I assign a random ID? Do you recommend a particular library? How can this random ID be persistent? Via a Google Analytics fallback cookie, I imagine?

What percentage is blocking is hard to say, as it varies widely by audience and other factors. However, it's definitely where I would start debugging. For the persistent ID, you can use our tracking plugin, which will set up a cookie for you. You can also do something yourself using a cookie and

crypto. randomUUID()

.

Thx you so much for yout time Ryan ! I let you know if it fix my issue !

Please follow up if you're still having trouble.