Thank you for your comment. I couldn't agree more. Such international tests are benchmarks. They are useful along with other indicators. Policy frameworks are also useful, and are also benchmarks (http://siteresources.worldbank.org/EDUCATION/Resources/278200-1221666119663/saber.html). How to improve performance is very country specific as you say, and schools are fundamentally important to helping compensate. But programs to help will be better informed and perform better if they are anchored in information about what works, what works in a particular context, and who needs what kind of assistance. The PISA tests come with a wealth of information on family and school characteristics. They need to be analyzed carefully and then used to help inform the national dialogue, along with other information, of course.