The Financial Post reports in its Thursday edition that record-breaking immigration is muddying the economic picture for the Bank of Canada, distorting key statistics and making its inflation battle more difficult. A Bloomberg dispatch to the Post reports that the surge of newcomers -- largely driven by an unplanned spike in foreign students and temporary workers -- has pushed Canada's population growth rate to 3.2 per cent, one of the fastest in the world. Canada added more than 1.2 million new residents in a year, an influx that has propped up gross domestic product, bolstered consumer demand and led to higher costs for homes, all while dragging on productivity and boosting the unemployment rate. It is creating a puzzle for policy-makers and economists. Population gains are complicating the BOC's ability to assess how restrictive interest rates truly are, says National Bank economist Stefane Marion. The BOC raised its overnight rate to 5 per cent with hikes last June and July after the economy showed surprising strength. Mr. Marion says: "Were the last 50 to 75 basis points warranted when it's all driven by a population surge which you can't do anything about? I think the [BOC] misread the situation."