I am reading an article about technology use in schools and I just wanted to share that they are discussing generalizability in small case studies. Basically, there are all these individual classroom pieces of evidence (increase math scores here, better writing skills there) but are based on case studies... the changes in these classroom are definitely applicable to other classes. However, state standardized tests are not increasing after huge technology upheavals & appropriate implementations. States are looking for ways to make generalized statements about technology's (hopefully) positive affect on learning. Many say that standardized tests simply can not measure the learning that is now occuring in classrooms (of 21st Century Skills).... so, clearly, these people have not taken a Research Methods class. If the data is not helping, find a new method of collecting a different type of data!
Not that you will want to read the whole article, but here it is anyway- http://www.nytimes.com/2011/09/04/technology/technology-in-schools-faces-questions-on-value.html?pagewanted=2&_r=4&smid=fb-share.