In the summer of 2004, a rural county in Texas had three separate instances of high school drivers causing serious automobile accidents. In the ten years prior to this summer, there had been only...

In the summer of 2004, a rural county in Texas had three separate instances of high school drivers causing serious automobile accidents. In the ten years prior to this summer, there had been only three such accidents involving teen drivers. The local superintendent of schools responded by requiring all high school students of driving age to take both beginner and advanced driver’s education courses. There were no such accidents the following summer. Why might you be cautious about concluding that the new driver’s education classes prevented automobile accidents?