The U.S. Department of Education’s National Center for Education Statistics (NCES) is the principal federal agency responsible for the collection, analysis and reporting of data on the condition of education in the United States. Dropout data from NCES examines rates within racial and ethnic groups, across gender groups, and across states and geographical regions. NCES defines the various types of dropout rates as follows.

• Averaged freshman graduation rates describe the proportion of high school freshmen who graduate with a regular diploma four years after starting ninth grade. This rate measures the extent to which schools are graduating students on time. The first school year for which NCES provides averaged freshman graduation rates is 2001-02. See related article.
• Event dropout rates describe the percentage of private and public high school students who left high school in a particular year (between the beginning of one school year and the beginning of the next) without earning a high school diploma or its equivalent. This rate is also referred to as an annual dropout rate. The Texas Education Agency reports the event rate (in addition to other rates). Definitions for TEA rates can be found on the TEA web site.
• Status dropout rates provide cumulative data on dropouts among young adults within a specified age range (usually: 15 to 24 years of age, 16 to 24 years of age, or 18 to 24 years of age). They measure the percentage of individuals who are not in school and have not earned a high school diploma or equivalency, irrespective of when they dropped out. These rates, which are higher than event rates because they include all dropouts, reveal the extent of the dropout problem in the population. (This rate focuses on an overall age group or cohort rather than on individuals.)
• High school status completion rates describe the proportion of individuals in a given age range who are not in high school and who have earned a high school diploma or equivalency credential (namely the GED certificate), irrespective of when the credential was earned. (This rate also is referred to as the school completion rate as the positive way of expressing the status dropout rate.)

Other types of measures include the following.

• Attrition rates measure the number of students lost from enrollment between two points in time (e.g., ninth grade and 12th grade enrollment four years later). Attrition data are similar to cohort data. IDRA releases adjusted attrition rates each year for the state of Texas.
• Cohort rates measure what happens to a cohort of students over a period of time. These rates provide repeated measures of a group of students starting at a specific grade level over time. These rates provide longitudinal data on a specific group of students, including background and contextual data.

The four NCES rates (the averaged freshman graduation rate, the event dropout rate, the status dropout rate, and the status school completion rate) and along with other traditional measures, such as the attrition rate and cohort dropout rates, provide unique information about high school dropouts, completers and graduates.

Though each rate has different meaning and calculation methods, each provides unique information that is important for assessing schools’ quality of education and school holding power.