The Globe and Mail reports in its Thursday, April 19, edition that business investment has emerged as the single biggest uncertainty looming over the Bank of Canada's path to higher interest rates. The Globe's David Parkinson writes that on Wednesday the BOC held its key interest rate steady at 1.25 per cent, while making it clear that it still plans on raising rates further. The question is not if, but when rates will climb again. Mr. Parkinson says that is anyone's guess, including the BOC's. "The pace is a significant question mark for us," said Governor Stephen Poloz after the BOC's release of its rate decision. He said, "We can't be definitive about when, or at what pace." One thing that is clear is that business investment has become central to answering that question. Perhaps the most interesting development in the BOC's update was its revelation that Canada's output gap actually opened up a bit in the past quarter. That implies an economy with a little bit of slack on its hands, which generally means it has more room to grow before we have to seriously start worrying about overheating, and inflation -- the two things the BOC generally worries most about.