Social media sites like Facebook and Twitter are sometimes used by scientists to quickly and cheaply gather data for studies, but according to new research these are biased and unreliable sources of human behavior. (Photo : Flickr: Maria Elena)

Social media sites like Facebook and Twitter are sometimes used by scientists to quickly and cheaply gather data for studies, but according to new research these are biased and unreliable sources of human behavior.

Computer scientists at Carnegie Mellon University and McGill University in Montreal warn that these social networking sites are populated by a very narrow section of society and "misrepresent the real world."

Thousands of research papers each year use these popular websites to gather human behavioral data, and yet researchers choose to ignore their shortcomings.

"Not everything that can be labeled as 'Big Data' is automatically great," co-author Juergen Pfeffer of Carnegie Mellon said in a statement.

For example, a news release from McGill University points out, only five percent of Twitter users are over the age of 65, compared with 35 percent for those aged 18-29. Pinterest is dominated by females aged between 25 and 34, and though Facebook has a diverse fan base, 76 percent of female internet users use the site compared with 66 percent of males.

"Most people doing real social science are aware of these issues," Pfeffer added. But it's hard to ignore their appeal to researchers.

"People want to say something about what's happening in the world and social media is a quick way to tap into that," Pfeffer said. "You get the behavior of millions of people - for free."

Pfeffer and his colleagues also note that social media sites can influence how a person normally behaves, and therefore it skews study results and limits what behavior can be measured.

Facebook, Twitter and other sites alike don't just create flaws in big study datasets, but they also have more far-reaching implications.

"Many of these papers are used to inform and justify decisions and investments among the public and in industry and government," assistant professor Derek Ruths said in the release.

The findings are described further in the journal Science.

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