Researchers at NORC at the University of Chicago are building a national database of health plan offerings in the Affordable Care Act’s individual and small-business marketplaces. As states post their final health plans and premiums for the 2015 open enrollment period, NORC will analyze changes in premium rates on The Commonwealth Fund Blog and track them in an interactive map. In the first of these blog posts, NORC’s Jon Gabel explains why early estimates of premium changes should be interpreted with caution.