Mary Beth asked:
Why can’t these little snippets of success count as “data”?
Because one thing we do have is plenty of happy customers and lots of anecdotal evidence. Robert’s response to Mary Beth’s question is worth noting and worth reading a few times at least:
They can and should. The problem is that they are “anecdotal” rather than “quantifiable”, and our society tends to discount anecdotal evidence in its reverence for “statistical data”. However, you should adduce these incidents as evidence (data) that students are meeting the Standard of “communities” by using the language outside the classroom and also conforming to the ACTFL policy statement on use of the target language. ACTFL therefore recommends that language educators and their students use the target language as exclusively as possible (90% plus) at all levels of instruction during instructional time and, when feasible, beyond the classroom. (Emphases mine)
You are on especially solid ground when you compare what “average” students did with the language in previous years with what they currently do. Even though it remains anecdotal, you can argue that it is “random sampling”.