6. Acknowledgements

We thank the Donner Foundation for its financial support. The analysis has been carried out by us with substantial assistance from Daniel Coster, Richard Cutler, Charles Everett, and Mark Hansen. We are grateful to the U.S. Census Bureau for making the P-12 data available and for many helpful explanations. We have served as consultants to the Freshpond Institute and as expert witnesses for the government in litigation over proposed adjustments of the 1980 and 1990 censuses.