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Appendix A: Methodology and Technical Notes


General Notes

Source of data. The numbers of high school diploma recipients and the student membership data presented in this report are taken from the Common Core of Data (CCD) State Nonfiscal Survey file, with one exception: counts of graduates by gender reported in table 8 are based on data taken from the CCD Local Education Agency Universe Survey file. The dropout data are reported on the CCD Local Education Agency Universe Survey file. State-level dropout data are created by aggregating LEA data to the state level. The membership data that were used to create the enrollment base (denominator) for the event dropout rate were taken from the CCD School Universe Survey. The grade-level membership data were aggregated to the LEA level from schools associated with the LEA.

The 2008–09 data were reported through the U.S. Department of Education's EDFacts system. American Samoa, the Northern Marianas, Guam, the U.S. Department of Defense dependent schools (overseas and domestic) and the Bureau of Indian Education did not report graduates or dropouts for the 2008–09 school year.

Missing data. When reporting results, NCES treats missing data within individual states differently than it treats missing data across all states, the District of Columbia, and other jurisdictions as a whole. An individual state is considered to have missing data if an item is reported for less than 80 percent of eligible students. If information is missing for some but no more than 15 percent of eligible students across the 50 states and District of Columbia, NCES calculates totals and identifies them as "reporting states" totals (rather than totals for the United States).

EDFacts accepted blank responses in 2008–09 school year reports and did not require that states distinguish among missing, not applicable, and "zero" values. Every effort was made to correctly identify responses as missing, not applicable, or zero after the fact, but it is possible that some blank responses may have been categorized incorrectly.

Totals. "Reporting states" totals are limited to the 50 states and the District of Columbia. Because not all, but at least 85 percent, of eligible students in the 50 states and the District of Columbia are represented in the graduation and dropout counts, these tables present a "reporting states" total. See "Missing data" (above) for more information.

Protecting the confidentiality of dropout and high school graduation data. It would be possible under some conditions to identify an individual student who dropped out of school or who was not awarded a regular diploma at the end of 12th grade. For example, if a state had 10 White students enrolled in 12th grade and only 1 White high school graduate, that graduating student could infer that all of the other White students had failed to graduate. The same situation could occur with dropouts. For example, if a state reported 15 White students enrolled in grade 9 at the beginning of a school year and 15 White 9th-grade dropouts, an outside observer could infer that all of the original students had dropped out. (These would be inferences because the CCD cannot distinguish between students who fail to graduate or who drop out and students who transfer out of state or into private schools.) The dropout and high school completion data were modified in order to guard against the identification of a specific 12th-grade student who did not receive a regular high school diploma or a specific student who dropped out of school. There were few threats to confidentiality in the state-level data. Reported numbers of graduates were increased or decreased slightly to protect against disclosure. These changes resulted in a minimal distortion of information and cannot be distinguished from unperturbed counts.

Data quality. There is variation in the degree of rigor with which the states or school districts verify their data. Those states that collect dropout or graduation data through student-level records systems are better able to verify students' enrollment and graduation status than are those agencies that collect aggregate data from schools and districts. In the past NCES did not audit state reports. Starting with the 2006–07 collection, NCES has been more aggressive in verifying data that do not appear to be accurate. During the 2007–08 collection, for example, if zero dropouts were reported for a school district that had a high school enrollment of more than 400 students NCES required confirmation from the state that the zero count was correct. Likewise, if zero diplomas were reported for a district with more than 20 twelfth graders then NCES required confirmation that the zero count was accurate. Barring confirmation, NCES recoded the submitted zero count, setting it to missing. NCES also required that some aggregate-level data be confirmed or revised. For 2008–09, Alabama, Michigan, and Wyoming were contacted because the submitted dropout counts produced dropout rate estimates that were low when compared to other states and data from earlier years. Illinois was contacted because the submitted dropout counts produced dropout rate estimates that were high when compared to other states and data from earlier years. Alabama, Illinois, Michigan, and Wyoming all confirmed the reported counts. Alabama, Illinois, and Wyoming all cited a new student data system that more accurately monitors dropout status as the reason for the magnitude of the differences. Puerto Rico was also contacted but did not reply to a request to revise its dropout data and those data were coded by NCES as missing. States have been made aware of the new NCES protocols and understand that NCES is working to develop further methods to audit their end of year data.

Discrepancies between dropout rates and graduation rates. The AFGR estimates the percentage of public high school students that receive a regular diploma within 4 years of their entry into 9th grade. Students that receive an alternative high school credential (i.e., a certificate of attendance or a high school equivalency degree) and those that take more than 4 years to complete high school are not considered on-time completers or dropouts. Thus one should not expect the AFGR and the dropout rates to account for all high school students. This considered, one would expect a high dropout rate to accompany a low graduation rate and vice-versa. This relationship is found for some states but not for every state. CCD staff is cognizant of this and intent on researching this more in the future.

Notes on High School Graduation Data

Differences in definitions of "graduate." State and local policies can affect the numbers of graduates reported. There are differences in what a high school diploma represents across states. The CCD defines a regular diploma as the high school completion credential awarded to students who meet or exceed coursework and performance standards set by the state or other approving authority. However, some states award regular diplomas to all students who meet completion requirements, regardless of the extent to which these requirements address the state or district's academic standards. For example, some states have in-school General Education Development (GED) programs that require fewer credit hours than a regular high school track, but lead to the award of regular diplomas. Other states award some form of alternative credential to students who meet some, but not all, requirements. For example, special education students who complete their individual education programs or regular education students in some alternative programs may receive a certificate of completion. As a result of different policies, students who receive a certificate of completion in one state might have been awarded a regular diploma in another.

Calculating the AFGR. The AFGR is the number of regular diploma recipients in a given year divided by the average of the membership in grades 8, 9, and 10, reported 5, 4, and 3 years earlier, respectively. For example, the denominator of the 2008–09 AFGR was the average of 8th-grade membership in 2004–05, 9th-grade membership in 2005–06, and 10th-grade membership in 2006–07. Ungraded students are prorated into grades 9 through 12. Averaging these three grades provides an estimate of the number of first-time freshmen in the class of 2005–06 freshmen in order to estimate the on-time graduation rate for 2008–09.

Treatment of ungraded students. Although the AFGR denominator is based on enrollments by grade, some states report ungraded students. To edit this, the data for ungraded enrollment counts were redistributed across grades in proportion to the graded enrollment of the state. For example, if 8th grade student accounted for 7 percent of all students in grades prekindergarten through grade 12 for the state, then 7 percent of the ungraded student count was prorated into the count of 8th-grade students. The redistributed counts of ungraded enrollments were added to the reported enrollment counts for the 8th, 9th, and 10th grades. For the distribution of the race/ethnicity detail, the same proportion used for the grade was used for each race/ethnicity detail. Ungraded enrollments account for approximately 1 percent of enrollments each year.

Cautions in interpreting the Averaged Freshman Graduation Rate. Although the AFGR was selected as the best of the available alternatives, several factors make it fall short of a true on-time graduation rate. First, the AFGR does not take into account any imbalances in the number of students moving in and out of the nation or individual states over the high school years. As a result, the averaged freshman class is at best an approximation of the actual number of freshmen, where differences in the rates of transfers, retention, and dropping out in the three grades affect the average. Second, by including all graduates in a specific year, the graduates include students who repeated a grade in high school or completed high school early and thus are not on-time cohort graduates in that year.

While the AFGR is a reasonable proxy at the aggregate national or state level, the potential effects of three factors should be taken into account when interpreting the results for individual states. First, if more high school students moved out of a population than transferred in during the high school years, the number of graduates in the numerator would be smaller and the estimated graduation rate would be lower than the actual on-time rate for that group of freshmen. On the other hand, if more high school students moved into a population than moved out during this 4-year period, the number of graduates in the numerator would be increased and the estimated on-time graduation rate would be higher than the actual rate for that group of freshmen. This can lead to estimated graduation rates of more than 100 percent for small groups; such cases have been edited to 100 percent in this report.

Second, including the estimate of 8th-graders from the previous year in order to remove the effect of freshmen who were retained, and thus are not first-time freshmen, ignores the fact that in some cases there may be real change in the number of 8th-graders relative to counts of 9th-graders due to transfers between public and private schools. If more students transfer to public schools during these years, using a count of 8th-graders that does not include those students would serve to artificially decrease the estimated number of 9th-graders, and as a result increase the graduation rate for that class. Conversely, if more students were to transfer out of public schools between the 8th and 9th grades, using the 8th-grade count that includes students leaving the population would artificially increase the estimated number of 9th-graders and in turn, decrease the graduation rate.

Third, there may be a tradeoff between the edits for retentions and grade specific differences in the number of dropouts. The use of the 10th-grade enrollment count helps to dampen the effect of 9th-grade retentions, but ignores the fact that 9th-grade dropouts result in a smaller 10th-grade population. Excluding these 9th-grade dropouts would lower the estimate of freshmen and as a result increase the graduation rate.

Missing and suppressed data. The Department of Defense dependent schools (domestic and overseas), the Bureau of Indian Education, American Samoa, the Commonwealth of the Northern Marianas Islands, and Guam did not report high school graduation data for 2008–09. California did not report graduation data for 2008–09. Data presented in this report and the accompanying data files for California have been imputed at the state level. Imputations were performed such that the prior year graduation rates were maintained at the race/ethnicity level. Nevada did not report graduates for the 2008–09 collection. Graduation data presented in this report and the accompanying data files for Nevada have been imputed at the state level based on the 2007–08 graduates and the enrollment data reported for school years 2004–05 through 2008–09. Imputations were performed such that the prior year graduation rate was maintained. The race/ethnicity graduate counts were derived from the prior year, 12th-grade-to-diploma ratio and then raked to the imputed total diploma count. Nevada did not report membership by race/ethnicity or gender in 2004–05; the 10th-grade enrollment from 2004–05 is required to calculate AFGR by race/ethnicity for 2008–09. Data for California and Nevada are not available by gender because no imputations were performed on the district-level data. Gender information is not included at the state level.

Maine's diploma data. Maine reported 1,169 diplomas awarded to students who attended private schools that receive a majority of their funding from public sources for the 2008–09 school year. Because students attending such schools were not reported by Maine prior to the 2007–08 school year, students attending them could not be included in the denominator for the AFGR. Therefore, these 1,169 diplomas were not included in the AFGR for Maine. Maine awarded 14,093 diplomas for 2008–09 and across all reporting states 3,037,926 diplomas were awarded. But, because of this discrepancy, Maine's AFGR was calculated using the 12,924 diplomas awarded to students attending public schools and the reporting states AFGR was based on 3,036,757 diplomas.

Notes on Dropout Data

Definition of a dropout. The CCD provides an event dropout count. An event dropout count represents the number of students dropping out each year. According to the CCD definition, a dropout is an individual who

  • was enrolled in school at some time during the previous school year;
  • was not enrolled at the beginning of the current school year;
  • has not graduated from high school or completed a state- or district-approved education program; and
  • does not meet any of the following exclusionary conditions: transfer to another public school district, private school, or state- or district-approved education program; temporary absence due to suspension or school-approved illness; or death.

The following statements apply for the purpose of this definition:

    • The school year is the 12-month period of time from the first day of school (operationally set as October 1), with dropouts from the previous summer reported for the year and grade in which they fail to enroll.
    • Individuals who are not accounted for on October 1 are considered dropouts.
    • A school completer is an individual who graduated from high school or completed a state- or district-approved educational program upon receipt of formal recognition from school authorities. A state- or district-approved educational program may consist of special education and district- or state-sponsored GED preparation.

Defining the school year. Not all states follow a fall-to-fall school year. The CCD dropout count is based on an October–September school year in which a student's dropout status is determined at the beginning of the year. Some states follow a July–June calendar in which a student's dropout status is determined at the end of the school year. Dropout rates in states that follow an alternative reporting calendar are comparable with rates for states that follow the October–September calendar (Winglee et al. 2000) and therefore data for states that follow alternative reporting calendars are published in the CCD data files.

Between-year (summer) dropouts. The CCD definition attributes dropouts to the grade and school year for which they do not meet their obligation. Students who complete 1 school year but fail to enroll in the next school year are counted as dropouts from the school year and grade for which they failed to return. For example, a student completing 10th grade in 2007–08 who does not enroll the next year would be reported as an 11th-grade dropout for 2008–09.

GED programs. Students who leave high school to enroll in adult education/GED preparation programs are reported as dropouts, unless the district tracks these students and reports as dropouts those who fail to complete the program. Students who have received a high school equivalency by October 1 are not dropouts regardless of where they prepared for the test, if the GED is an accepted high school credential in the state.

Calculating the event dropout rate. The event dropout rate for a given grade is the number of dropouts from that grade divided by the number of students enrolled in that grade at the beginning of the school year. For example, the 10th-grade event dropout rate for 2008–09 is the number of 2008–09 10th-grade dropouts divided by the number of students in 10th grade at the beginning of the 2008–09 school year. Beginning with the 2007–08 school year, states reported ungraded dropouts as a separate category. Therefore, ungraded students and dropouts are not prorated into any single grade. They are prorated in the aggregate grade 9–12 high school dropout counts and rates. The proration process is the same as that used for the AFGR.

Missing and suppressed data. Vermont suppressed all dropout counts less than 10 prior to submitting these data to EdFacts for the 2008–09 school year. Because the suppressed data represented districts that included more than 90 percent of the state's student membership, NCES suppressed the 2008–09 district level dropout data for Vermont. Vermont also suppressed these low counts when reporting for the state as a whole resulting in the suppression of the race/ethnicity detail for Vermont at the state level. Utah did not report data by race/ethnicity or gender at the school district or state levels. In addition, Maryland did not report dropout data by gender. California and Nevada did not report completion or dropout data for 2008–09. Data presented in this report and the accompanying data files for California and Nevada has been imputed at the state level. Imputations were performed such that the prior year dropout rates were maintained at the race/ethnicity level. Data are not available by gender because no imputations were performed on the district-level data. Beginning with 2007–08, NCES asks states and other jurisdictions to confirm or revise any dropout data that would infer a dropout rate of less than 1 percent. As the dropout count reported for Puerto Rico would infer a dropout rate of less than 1 percent, and Puerto Rico did not respond to inquiries made by Census Bureau analysts, NCES has suppressed the dropout count and rate for Puerto Rico. This is part of an ongoing effort on the part of the CCD to ensure more accurate dropout and completer data. The Department of Defense dependent schools (overseas and domestic), the Bureau of Indian Education, American Samoa, Guam, and the Commonwealth of the Northern Marianas Islands did not report any dropout data for the 2008–09 school year.

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