The Mortgage Bankers Association recently expanded its mortgage rates survey to include more than 75% of all mortgage originations, up from approximately 50% previously. As a result of the modification, data tracking rates shifted back to the middle of January. For the most part, changes to separate categories of mortgage products remained little changed. For Federal Housing Administration-backed mortgages however, the change in effective mortgage rate reveals that borrowers' loans on average cost less than originally thought (see chart below): The mortgage strategies group of Sandler O’Neill & Partners, a registered broker-dealer, put together the information in a note to clients. "Like the conventional universe, the 4.5% coupon has now moved completely into the 40bp refinancing window," said Scott Buchta, managing director at Sandler O'Neill. "Higher (mortgage insurance) fees and a lack of a HARP-like program may prevent some FHA borrowers from refinancing." The average FHA rate was actually lower than previously reported as the new expanded survey increased the amount of data that they were getting in. That means that FHA loans are actually more affordable than previously reported, the data states. Write to Jacob Gaffney. Follow him on Twitter: @JacobGaffney.