You can't. At least not by their views. As a group, tweeters - people who use Twitter to post short messages and observations - defy public trends and opinion polls, according to a year-long study by Pew Research.
Sometimes they're liberal, sometimes conservative*, sometimes negative, sometimes not - but never in the same manner as the rest of the world.
"The reaction on Twitter to major political events and policy decisions often differs a great deal from public opinion as measured by survey," Pew notes. "This is the conclusion of a year-long Pew Research Center study that compared the results of national polls to the tone of tweets in response to eight major news events, including the outcome of the presidential election, the first presidential debate and major speeches by Barack Obama."
Compared to the general public, tweeters were more "liberal" in their:
reaction to President Obama's victory over conservative challenger Mitt Romney in the November presidential election
assessment of Obama's performance over Romney in their first debate, when tweeters said Obama won while general opinion polls crowed Romney
reaction to a federal court ruling that a California ban on same-sex marriage was unconstitutional - tweeters generally approved the ruling, the public did not
But tweeters were more "conservative" in their reaction to Obama's January Inaugural Address, his February State of the Union speech, and in his appointment of Sen. John Kerry as Secretary of State, Pew said, noting that tweeters tended to express a more negative than positive view of those, opposite to general public opinion.
"The lack of consistent correspondence between Twitter reaction and public opinion is partly a reflection of the fact that those who get news on Twitter – and particularly those who tweet news – are very different demographically from the public," Pew said.
"The overall reach of Twitter is modest. In the Pew Research Center’s 2012 biennial news consumption survey, just 13% of adults said they ever use Twitter or read Twitter messages; only 3% said they regularly or sometimes tweet or retweet news or news headlines on Twitter.
"Twitter users are considerably younger than the general public and more likely to be Democrats or lean toward the Democratic Party. In the 2012 news consumption survey, half (50%) of adults who said they posted news on Twitter were younger than 30, compared with 23% of all adults...
"In another respect, the Twitter audience also is broader than the sample of a traditional national survey. People under the age of 18 can participate in Twitter conversations, while national surveys are limited to adults 18 and older. Similarly, Twitter conversations also may include those living outside the United States."
* Liberal and conservative are relative terms. I make no attempt in this blog post to define them or to apply any definition Pew might have used, except to say that some American "liberals" could lead a right wing party in Europe. As with tweeters, let's not pigeonhole!