Did Facebook's Experiment Violate Ethics?
Facebook essentially sought to manipulate people's mood. This is not a trivial undertaking. What if a depressed person became more depressed? Facebook says that the effect wasn't large, but it was large enough for the authors to publish the study in a major science journal.
This experiment is scandalous and violates accepted research ethics.
Read more: http://www.cnn.com/2014/07/02/opinion/klitzman-facebook-experiment/