The thing is I'm sure Facebook didn't build the AB test framework for this study. We know not all your friends posts show up in your feed. They certainly have

The thing is I'm sure Facebook didn't build the AB test framework for this study. We know not all your friends posts show up in your feed. They certainly have been using AB testing to improve what stories they show to users. I also bet they have been using this framework to optimize ad revenue. This causes a problem if the study was wrong because it manipulated users then wouldn't all AB testing be wrong for the same reasons.