I think everyone will agree that results are probably the key to understanding how effective K-12 education is or isn't. The question becomes what results need to be analyzed. How can we be sure the examination of performance provides valid and reliable data? That is to say, will the examination measure the same data each year again and do all participants have an equal opportunity?
Here is a site, Measuring Up, that provides result data on every state for K-12 over a number of years on a variety of topics. It also allows you to compare state results using different topics. For example, you can compare AZ, CA, and NY on subjects within participation, achievement, and affordability. Perhaps the best stat here is being able to see the number of students going on to two or four colleges, after all isn't that the ultimate goal of high school? Sure a high school diploma is great, but if you don't go to a technical school, college or university to get some skills you're bound to be part of the service sector working for minimum wage.
Check out Measuring Up and tell me what you think.