Student ratings of instruction have been the subject of over 2,000 published research studies. The vast majority of these offer assurance that ratings possess acceptable reliability (if there are at least 10 raters). Ratings have also been shown to be reasonably valid in a number of different ways. Perhaps the most convincing of these are the studies of multiple sections of large courses in which student ratings were highest for instructors whose students made the best grades on a common final examination.