http://www.digitaljournal.com/technology/scientists-say-social-media-not-accurate-for-sociological-studies/article/417947

Scientists say social media not accurate for sociological studies

Posted Nov 29, 2014 by William Suphan
Scientists at two universities have determined that social media sites like Twitter and Facebook are not representative of society in general and should not be used for studies.
At McGill University in Montreal, and Pittsburgh's Carnegie Mellon University, scientists have been examining data regarding sociological studies that use social media as source material. They've found that what is shared on sites such as Pinterest, Twitter and Facebook is not truly representative of society due to many demographics being over and under-represented, according to The Telegraph.
For instance, they found that, for Twitter, only 5 percent of the over-65 demographic make use of such sites, but for the 19-39 group, it is around 35 percent. Also, far more men use Twitter than women.
Alternately, Pinterest's largest demographic is females aged 25 to 34.
Instagram's main users are generally urban young adults and non-whites.
While Facebook has the widest appeal, the lack of a "dislike" button makes for inaccurate determinations of how people really feel regarding posted content. Eleven percent more women are on Facebook than men.
An assistant professor of Computer Science at McGill University, Derek Ruths, stated, "A common assumption underlying many large-scale social media-based studies of human behaviour is that a large-enough sample of users will drown our noise introduced by peculiarities of the platform’s population. These sampling biases are rarely corrected for, if even acknowledged."
Interest bias is also evidenced in the way that such sites tend to direct specific content to users rather than displaying all available content. Users are directed to topics they've viewed before, which means users may not access and comment on content that they otherwise might have.
The scientists claim that researchers in the media and in many fields of study tend to base many findings on social media content and this is providing a largely inaccurate view of the real world, and relies only on a very narrow portion of society.
"Many of these papers are used to inform and justify decisions and investments among the public and in industry and government," said Ruths.