09-05-16

# Traffic allocation not working

Hi! For some reason my allocated traffic does not split 50/50 between Original and Variation #1. It's been running for 11 days and we have 66% on the Original and 34% on the Variation #1. Anyone knows why it does not split evenly?

Level 2

CouchPsycho 09-05-16

## Re: Traffic allocation not working

Hi,

is it a new experiment or do have restarted ( and/or modified) an existing one? I hope, traffic is high enough, too?

Kind regards

Michael

"the essence of the creative act is to see the familiar as strange." (anonymous)
Level 10
markusp80 09-05-16

## Re: Traffic allocation not working

Hi! It's a new project and it's been running for 11 days. It's only been 53 unique visitors to that site where I'm running the test, but still I think that 66% and 34% is somewhat uneven distribution of the traffic, wouldn't you say?

Level 2
CouchPsycho 09-05-16

## Re: Traffic allocation not working

Hi,

from my point of view, there are to less visitors. You can calculate the probability for this using Bernoulli-distribution but unless you have at least 100 visitors, i won't get nervous in any way.

Kind regards

Michael

"the essence of the creative act is to see the familiar as strange." (anonymous)
Level 10
markusp80 09-05-16

## Re: Traffic allocation not working

Ok, thanks! We will await more visitors. We can already see a trend, but it will be more reliable with more visitors of course.
Level 2
DanielQ 09-13-16

## Re: Traffic allocation not working

[ Edited ]

Just to clarify how Optimizely allocates traffic:

When Optimizely buckets a visitor into an experiment that has a 50/50 traffic allocation, it "flips a coin" for each visitor. That is, each visitor has a 50% chance of being bucketed into one of the variations. Because of this, sometimes distributions will look a little lopsided when there's not a lot of traffic. Statistically, it should even out as you get more visitors

Daniel Quick, Optimizely
Optimizely
markusp80 09-14-16

## Re: Traffic allocation not working

Thanks Daniel. But how about this: I currently have close to 100 visitors in 20 days on the page I am running the A/B test on. What happens if I change the traffic allocation to 90% on the variation (which has about 40% right now) to even it out?

Level 2
DanielQ 09-14-16

## Re: Traffic allocation not working

Hello! Changing the traffic allocation for your variations after starting an experiment will compromise your results. You can read more about that here, here, and here. To protect the integrity of your results, we recommend that you do not alter this variable.

Daniel Quick, Optimizely
Optimizely