Madison School District Superintendent Dan Nerad (1.5MB PDF):

DPI has two official models for calculating high school completion rates. Regardless of which model is used, MMSD has lagging graduation rates for among its student subgroups.
As required by NCLB, a new four-year cohort graduation rate calculated by DPI provides an “on time” graduation rate. This calculation will eventually replace the so-called “legacy rate” which DPI has used for the past several years. That means that we could characterize our graduation rates in the following two ways: