Twitter an unreliable barometer of U.S. public opinion

Pew Research found that twitter results don't consistently track overall public opinion polls and offered some reasons why this is so:

• Twitter users are younger overall, as far fewer seniors use it
• Public opinion polls don't survey people younger than 18, but twitter users can be under 18
• Many twitter users don't live in the US
• The subsets of twitter users who tweet about news events shifts among users who are personally invested in a particular issue

The study also found that while twitter users were more liberal in reacting to Obama's reelection, his first debate performance and California's ruling to overturn prop 8, they were more conservative in reacting to Obama's 2012 State of the Union address, John Kerry after his nomination for Secretary of State, and Obama's second inaugural speech