The middle class used to be fairly easy to define: an affordable home, good schools, a little money saved for a family vacation. But today, almost half of all Americans live with certain anxiety because of an uncertain economy. 

That's why WGBH News is focusing on rediscovering the middle class. Reporter Stephanie Leydon kicks off our series with a look at why more and more people are feeling squeezed out.

Jodi Beggs is an economics lecturer at Northeastern University and writes the blog Economists Do It With Models.