Original sentence: The validity of the Challenge Index has been strongly criticized by education analysts Andrew J
Edited sentence: Furthermore, since registration to take the AP/IB exams is voluntary, even the data used in the index calculation does not provide an accurate measure of the number of students taking these college preparatory classes, which, as studies have shown, is the most important factor in determining future success in college.In addition, the validity of the Challenge Index has been strongly criticized by education analysts Andrew J.It only measures how many students took the AP/IB exams.Unfortunately, using the Challenge Index to assess a school's academic performance is flawed, and can be misleading since it does not report, nor measure, the actual AP or IB scores that students achieve