NEW YORK - Bad credit has supplanted terrorism as the gravest immediate risk threatening the economy, a key national research group reported Monday. Borrowers' withering ability to pay their bills and the subsequent fallout in the credit markets this summer topped the list of short-term risks on peoples' minds, according to a survey of 258 members conducted by the National Association of Business Economics. NABE, a Washington-based association, said 32 percent of its surveyed members cited loan defaults and excessive debt as their biggest near-term concern. Only 20 percent of members cited defense and terrorism as their biggest immediate worry,...