wealth of his neighbors, can be thought of as an ex ante idea.17 It led to the formulation of the guaranteed tax base (GTB) formula for distributing state aid to school districts, which, in its pure form, is constructed so that districts that levy the same tax rates will spend the same amount of money per pupil.18 GTB has also been used as a way to achieve ex ante taxpayer equity based on the idea that potential tax rate equity is a good measure of taxpayer equity. 19
A large amount of school finance research as well as legislative and court activity has focused on the ex post definitions of wealth neutrality. Ex post analysts look for statistical relationships (associations) between education, usually measured in dollars, and school district wealth. They ask whether or not there is an actual association between educational inputs and ability to pay. Much of the earlier work focused on district-level inputs (per-pupil dollars or per-pupil resources, such as staff or teachers) and per-pupil property wealth.
The unit of analysis for wealth neutrality has been the state and its districts. It is not a relevant concept at the school level because schools do not have the authority to levy taxes, but rather districts and/or states levy taxes for the schools within them.20 At the beginning of the period, the focus was on inputs; now, in addition, users are interested in outputs and outcomes.
In Private Wealth and Public Education (1970), Coons et al. set the stage for court and legislative activity in the 1970s in three ways: by establishing an ex ante principle that could be used to argue for judicial intervention on the basis of the Fourteenth Amendment (or its state constitutional versions), by demonstrating that the specifics of current state financing systems violated the principle both ex ante and ex post, and by proposing a new system that would remedy the problem. Their ex ante principle was that a child's education should not depend on his neighbor's wealth, and their analyses showed that current financing systems did not prevent such dependence. They proposed the district power equalizing finance formula (DPE, also known as guaranteed tax base or GTB) as a way to make a child's education depend on local effort not wealth. Explicit in their work was an emphasis on inputs21 and a remedy that preserved local choice.22
Trite but true, the rest is history. Private Wealth and Public Education wrote the script for Serrano and many cases that followed, such as Levittown (1982) and Abbott v. Burke (1985).23 It also stimulated analytical, legislative, and legal work. Martin Feldstein (1975) showed that the power-equalizing formula does not in theory sever the relationship between a community's expenditures per pupil and its wealth per pupil. School districts make decisions about spending per pupil based on their local tax price, income levels of residents, and other taste and socioeconomic factors. Feldstein demonstrated that district power equalizing does not correctly offset the effects of DPE's tax price and other wealth-related factors and, therefore, districts do not respond in ways that break the positive wealth-spending relationship.24
Berne and Stiefel's The Measurement of Equity in School Finance (1984) presented a variety of ex post measures of wealth neutrality, including correlations,