[gammarator]

A/B tests are different, though: in aggregate, they should make your website better for me, the user. Here the user is just fodder for an academic's fairly trivial journal article (my friends' feelings affect my feelings!).

Who decides what experiments social scientists get to run on 1/7th of the world's population?

[akerl_]

They only make the site better for you if you're on the "winning" side. If A/B tests made the site better for everyone being tested, they'd not be very useful. Unless you mean "they should make your website better for me [after the test is done]", in which case they have the same goal as Facebook's study.

[gammarator]

That's what I said: A/B tests improve the site "in aggregate."

The goal of this study was not to improve the site, though: it was to test a hypothesis about social psychology.

[yincrash]

The goal of the study _is_ to improve the site. Facebook wants the users to return to the site, and users who become happier when using the site do that. Facebook isn't paying its data scientists to perform studies that have no meaningful use.

[akerl_]

I sincerely hope you're not making the case that testing a hypothesis for a scientific paper is not a valid reason to perform such an experiment, but improving a website is.