The “long run” isn’t everything, but it’s something, which is to say it’s relevant. Studying it, then, is productive. It shouldn’t dominate decisions for designing and managing asset allocation, but it’s a great place to start.
The long run is everywhere when perusing the latest edition of Ibbotson SBBI 2009 Classic Yearbook. For the uninitiated, the book is a feast of data, reviewing all the usual measures of stocks, bonds and now REITs and a touch of commodities. Here is the epitome of slicing and dicing the numbers when it comes to investment research, at least when defined in the dead-tree medium. You’re not really familiar with the trends and the profiles of the major asset classes until you’ve spent some time poring over SBBI.