After facing global flak over its users' mood study, the social networking site Facebook has given researchers clear guidelines for further research.

 

 "If proposed work is focused on studying particular groups or populations (such as people of a certain age) or if it relates to content that may be considered deeply personal (such as emotions) it will go through an enhanced review process before research can begin," Facebook chief technical officer Mike Schropefer wrote in a blog post.

 

 Researchers altered nearly 700,000 users' news feeds to show either only happy or sad posts from friends in the mood study that was published in the journal Proceedings of the National Academy of Sciences.

 

 They found that the tone of friends' posts had a corresponding effect on Facebook users' moods.

 

 "It is clear now that there are things we should have done differently," Schropefer said.

 

 "For example, we should have considered other non-experimental ways to do this research. The research would also have benefited from more extensive review by a wider and more senior group of people. Last, in releasing the study, we failed to communicate clearly why and how we did it," he wrote.

 

 Now, "we have created a panel including our most senior subject area researchers, with people from our engineering, research, legal, privacy and policy teams that will review projects falling within these guidelines. This is in addition to our existing cross-functional, privacy review for products and research," he maintained.