A new Pew study shows that the conversation on Twitter is more often than not out of sync with national attitudes on major political events:

Of the eight events that the Pew Research Center tracked since the beginning of last year, there were two – Mitt Romney’s selection of Paul Ryan as his vice presidential running mate and the Supreme Court’s ruling on the 2010 Affordable Care Act – when the reaction on Twitter paralleled public opinion.

When Mitt Romney tapped Ryan as his running mate, it received a more negative than positive reaction both from the general public and in the conversation on Twitter. And when the Supreme Court handed down its ruling upholding the health care law in June 2012, public reaction was split: A national survey found 36% approving and 40% disapproving of the Court’s decision. The reaction on Twitter was about the same: Among those offering a viewpoint, roughly half were positive comments and half were negative.

Events that tilted more conservative in tone on Twitter than the nation as a whole were… President Obama‘s 2012 State of the Union speech and his second Inaugural address.

Events that tilted more liberal in tone on Twitter: Obama’s reelection, his performance in first debate (which most people saw as a flop) and a court ruling that declared California’s same-sex marriage ban unconstitutional. The tone in tweets about both the Romney and Obama campaigns also tended to be more liberal.

Reasons for the divide between Twitter tone and national sentiment: Twitter users trend mostly younger, the platform still has a relatively small number of users and many of them are from tweeting from outside the U.S.