The McDonald’s fast-food chain may have been responsible for at least half the jobs created in the United States in May, according to numbers reported byMarketWatch.Morgan Stanley calls it the “McDonald’s Effect,” according to MarketWatch’s Washington Bureau Chief Steve Goldstein — an estimate that as many of the 30,000 of the 54,000 jobs added in May were the result of a hiring binge by the hamburger chain, according to The Weekly Standard “McDonald’s ran a big hiring day on April 19 — after the Labor Department’s April survey for the payrolls report was conducted — in which 62,000 jobs were added,” MarketWatch reported. “That’s not a net number, of course, and seasonal adjustment will reduce the Hamburglar impact on payrolls. (In simpler terms — restaurants always staff up for the summer; the Labor Department makes allowance for this effect.) Morgan Stanley estimates McDonald’s hiring will boost the overall number by 25,000 to 30,000. The Labor Department won’t detail an exact McDonald’s figure — they won’t identify any company they survey — but there will be data in the report to give a rough estimate.”