The U.S. economy contracted early this year as harsh weather and a strong dollar sapped demand for American goods, underscoring the choppiness of an expansion that has struggled to lift off. Gross domestic product, the broadest sum of goods and services produced across the economy, shrank at a 0.7% seasonally adjusted annual rate in the first quarter, the Commerce Department said Friday. The agency previously estimated output grew 0.2% from January through March. The revision, near economists’ expectation of a 1% contraction, showed how the world’s largest economy remains vulnerable to shocks as it struggles to regain its vigor. The dip, expected to be short-lived, marked the third quarterly contraction since the economy emerged from recession in mid-2009. “When you’re this weak, little things can knock you off course, whether it’s the Arab spring, the earthquake or ‘Snowmageddon,’ ” economist Dan Greenhaus of brokerage firm BTIG said. “We have […]