Exercises 13.1 For years, the state of Illinois has administered the Illinois State Aptitude Test (ISAT) to third, fifth, and eighth graders. For much of this time, the test was relatively low stakesnot tied to promotion to the next grade, teacher com- pensation, school resources, and so on. The stakes changed in 2002, when the ISAT became the test that the Chicago Public Schools used to comply with the federal No Child Left Behind law. Consider two cohorts of students: students who were fifth graders in 2001 and students who were fifth graders in 2002. Both of these groups of stu- dents took the ISAT in third grade when it was low stakes. The students who were in fifth grade in 2001 also took the ISAT in fifth grade when it was low stakes. But the students who were in fifth grade in 2002 took their second ISAT when it was high stakes. Make a two-by-two table showing how we could learn about the average effect of high-stakes testing on student test scores using a difference-in-differences design if we had data on the average test scores of these two cohorts of students when they were fifth and third graders