A primer on understanding health care cost trends: the story behind the numbers.

Virtually every study shows that rates of increase in health care costs have declined throughout the 1990s, but often the bottom-line numbers differ. There are numerous reasons for this disparity, including which data are used and how researchers analyze them. Unfortunately, there is no ideal source of data; the best sources vary widely with regard to accuracy, timeliness, and, most important, whether the information lines up with the questions that are being asked. This Issue Brief provides information about how to understand what the numbers really represent.