CHRISTOPHER T. CROSS

This conference brings together statisticians, researchers and policy makers, three groups that must talk together, but—as we know—sometimes have difficulty finding the time.

But this type of communication is vital. Surveys and other data collection systems must provide the information policy makers need at the time they need it and in a form they can use. For their part, policy makers need to be more clear about what their needs are and about what information is most useful. This conference provides an opportunity to engage in this sort of give and take.

The subject of this conference—teacher supply, demand, and quality—is clearly of central importance to education. The implications of the relevant statistics and research affect the most important determinant of learning—classroom teachers.

Yet this is a field still very much in its infancy. As seen in the papers presented at this conference, debate continues over such basic issues as what to measure, how to measure it, and even when to measure it. Even more work remains to be done in designing models that predict shortages ahead of time, so that policy makers can respond in time.

Nonetheless, progress is being made on a number of important issues. We have learned, for example, that yearly attrition rates can be deceptive for predicting future needs since many departing teachers eventually return to teaching after a few years. Nearly 40 percent of current teachers have taken just such a break and returned to the classroom (Feistritzer, 1990).

We have also learned that, while aggregate data is important, more attention must be focused on key subject fields that may face particular