Diplomas Count uses the Cumulative Promotion Index (CPI) method to calculate high school graduation rates for American public schools. This approach allows the EPE Research Center to compute the percent of public high school students who graduate on time with a diploma.
The CPI method represents the high school experience as a process rather than an event, capturing the four key steps a student must take in order to graduate: three grade-to-grade promotions (9 to 10, 10 to 11, and 11 to 12) and ultimately earning a diploma (grade 12 to graduation). Each of these individual components corresponds to a grade-promotion ratio. Multiplying these four grade-specific promotion ratios together produces the graduation rate.
Different methods for calculating a graduation rate may employ different definitions of a 鈥済raduate.鈥� The CPI method adheres to federal guidelines and only counts students receiving standard high school diplomas as graduates. Recipients of General Educational Development diplomas, certificates of attendance, and other nondiploma credentials are treated as nongraduates in this context.
The 2013 edition of Diplomas Count presents a new analysis of graduation rates with a focus on the high school class of 2010, the most recent year for which information is available. The CPI analysis is based primarily on data from the U.S. Department of Education鈥檚 Common Core of Data (CCD), an annual census of all public schools and school districts in the country. In rare situations where key data points are not available on a statewide basis from the CCD, the EPE Research Center obtains comparable graduation data directly from the state education agencies.
The Department of Education鈥檚 National Center for Education Statistics, which manages the CCD, periodically releases updated versions of CCD data files that incorporate revisions or corrections submitted by the states. Every year, the EPE Research Center recomputes its full historical CPI analysis to reflect any revised data released since the prior edition of Diplomas Count. Such data revisions are typically minor and do not substantively change CPI results as previously reported. However, during summer 2012, the NCES engaged in a significant quality review of CCD data from the 2009-10 and 2010-11 school years. The review identified numerous irregularities, which the states were asked to address as part of an amended data release. In at least some cases, the revisions were large enough to produce noticeable changes in previously published CPI results for the class of 2009, including some state and national statistics.
The EPE Research Center calculates graduation rates for school districts that issue diplomas (i.e., those with a 12th grade). To provide fuller and more representative coverage of the student population, the center used a multivariate statistical model to impute 2010 graduation rates for certain districts where a directly calculated rate was not available. Statistics for the nation and states are generated by aggregating district-level data upward.
