Argues that the loss-function analysis used to adjust the census of 1990 depends on estimating probable errors in census and adjustment and that data from field-validation projects does not provide estimates accurate enough for the purpose. The loss-function analysis is actually driven by assumptions, not data. (SLD)

Data from the Child and Adolescent Trial for Cardiovascular Health, a school-based field trial, are used to illustrate the use of process evaluation for understanding study outcomes. Teacher characteristics and fidelity to the program model had direct and independent effects on student outcomes from the program. (SLD)