I love that the author of the paper responded to this. Thank you HN, and Andy. I suspected it was hard or else, I assume, you would have done it. But I thought

I love that the author of the paper responded to this. Thank you HN, and Andy. I suspected it was hard or else, I assume, you would have done it. But I thought it was hard because getting everyone to take a standardized test before and after the courses would be hard, not because even the contact information was not available! Also, what do you mean exams are unreliable? Is there something you can point me to. I did not know that was the case.