The battle of the number crunchers continues. In 1992, a Boston Fed review of thousands of mortgage files found a pattern of lending bias against minorities. But a recent Fed study reached a different conclusion. And now a draft report by a Federal Deposit Insurance Corp. economist contends that the 1992 Boston Fed study was flawed. The GOP will use the new reports to rein in the Clintonites' enforcement of fair-lending and community-reinvestment laws.