The Condition of Education is available in three forms: this print volume for 2012 and on the National Center for Education Statistics (NCES) website, an electronic version, and a downloadable e-book. The Condition of Education website includes the entire content of the 2012 print volume, plus special analyses from the 2000 through 2011 editions, as well as selected indicators from earlier editions of The Condition of Education. (See pages 1 through 6for a list of all the indicators that appear on The Condition of Education website.) The print volume of The Condition of Education 2012 is divided into three sections of indicators. Each indicator consists of one page of key findings and technical notes, two figures on the adjacent page, and one or more tables, found in Appendix A. The tables feature the estimates used in the indicator discussion as well as additional estimates related to the indicator. Where applicable, tables of standard errors for estimate tables are available on the NCES website. Additional information on data sources can be found in Appendix B. Information on analyses conducted, definitions of variables, and measures can be found in the notes in Appendix C. Finally, a glossary of key terms, a bibliography, and an index are featured in Appendixes D through F. This icon on the main indicator page lists references for related indicators, tables, glossary terms, and other sources that provide more information related to the indicator. Indicators use the most recent national and international data available during production from either NCES or other sources relevant to the indicator. When the source is an NCES publication, such as the Digest of Education Statistics, the publication can be viewed on the NCES website (http://nces.ed.gov/pubsearch).
Data Sources and Estimates
The data in this report were obtained from many different sources—including students and teachers, state education agencies, local elementary and secondary schools, and colleges and universities—using surveys and compilations of administrative records. Users of The Condition of Education should be cautious when comparing data from different sources. Differences in aspects such as procedures, timing, question phrasing, and interviewer training can affect the comparability of results across data sources. Most indicators in The Condition of Education summarize data from surveys conducted by NCES or by the U.S. Census Bureau with support from NCES. Brief explanations of the major NCES surveys used in this edition of The Condition of Education can be found in Appendix B – Guide to Sources of this volume. More detailed explanations can be obtained on the NCES website under “Surveys and Programs.” Appendix B also includes information on non-NCES sources used to compile indicators, such as the American Community Survey (ACS) and the Current Population Survey (CPS). These are Census Bureau surveys used extensively in The Condition of Education. For further details on the ACS, see http://www.census.gov/acs/www/. For further details on the CPS, see http://www.census. gov/cps/. Data for indicators reported in this volume are obtained primarily from two types of surveys: universe surveys and sample surveys. In universe surveys, information is collected from every member of the population. For example, in a survey regarding certain expenditures of public elementary and secondary schools, data would be obtained from each school district in the United States. When data from an entire population are available, estimates of the total population or a subpopulation are made by simply summing the units in the population or subpopulation. Since a universe survey is often expensive and time consuming, many surveys collect data from a sample of the population of interest (sample survey). For example, the National Assessment of Educational Progress (NAEP) assesses a representative sample of students rather than the entire population of students. When a sample survey is used, statistical uncertainty is introduced, because the data come from only a portion of the entire population. This statistical uncertainty must be considered when reporting estimates and making comparisons. Various types of statistics derived from universe and sample surveys are reported in The Condition of Education. Many indicators report the size of a population or a subpopulation, and often the size of a subpopulation is expressed as a percentage of the total population. In addition, the average (or mean) value of some characteristic of the population or subpopulation may be reported. The average is obtained by summing the values for all members of the population and dividing the sum by the size of the population. An example is the annual average salaries of full-time instructional faculty at degree-granting postsecondary institutions. Another measure that is sometimes used is the median. The median is the midpoint value of a characteristic at or above which 50 percent of the population is estimated to fall, and at or below which 50 percent of the population is estimated to fall. An example is the median annual earnings of young adults who are full-time, full-year wage and salary workers.
Standard Errors
Using estimates calculated from data based on a sample of the population requires consideration of several factors before the estimates become meaningful. When using data from a sample, some margin of error will always be present in estimations of characteristics of the total population or subpopulation because the data are available from only a portion of the total population. Consequently, data from samples can provide only an approximation of the true or actual value. The margin of error of an estimate, or the range of potential true or actual values, depends on several factors such as the amount of variation in the responses, the size and representativeness of the sample, and the size of the subgroup for which the estimate is computed. The magnitude of this margin of error is measured by what statisticians call the “standard error” of an estimate. When data from sample surveys are reported, the standard error is calculated for each estimate. The standard errors for all estimated totals, means, medians, or percentages reported in the tables of The Condition of Education can be viewed on the NCES website. In order to caution the reader when interpreting findings in The Condition of Education, estimates from sample surveys are flagged with a “!” when the standard error is 30 percent of the estimate or greater, and suppressed with a “†” when the standard error is 50 percent of the estimate or greater.
Data Analysis and Interpretation
When estimates are from a sample, caution is warranted when drawing conclusions about one estimate in comparison to another, or about whether a time series of estimates is increasing, decreasing, or staying the same. Although one estimate may appear to be larger than another, a statistical test may find that the apparent difference between them is not reliably measurable due to the uncertainty around the estimates. In this case, the estimates will be described as having no measurable difference, meaning that the difference between them is not statistically significant. Whether differences in means or percentages are statistically significant can be determined using the standard errors of the estimates. In this publication and others produced by NCES, when differences are statistically significant, the probability that the difference occurred by chance is less than 5 percent, according to NCES standards. Data presented in The Condition of Education do not investigate more complex hypotheses, account for interrelationships among variables, or support causal inferences. We encourage readers who are interested in more complex questions and in-depth analysis to explore other NCES resources, including publications, online data tools, and public- and restricted-use datasets at http://nces.ed.gov. For all indicators in The Condition of Education that report estimates based on samples, differences between estimates (including increases and decreases) are stated only when they are statistically significant. To determine whether differences reported are statistically significant, two-tailed t tests at the .05 level are typically used. The t test formula for determining statistical significance is adjusted when the samples being compared are dependent. The t test formula is not adjusted for multiple comparisons. When the difference between estimates is not statistically significant, tests of equivalence can be used. An equivalence test determines the probability (generally at the .15 level) that the estimates are statistically equivalent, that is, within the margin of error that the two estimates are not substantively different. When the difference is found to be equivalent, language such as “x” and “y” “were similar” or “about the same” has been used. When the variables to be tested are postulated to form a trend, the relationship may be tested using linear regression, logistic regression, or ANOVA trend analysis instead of a series of t tests. These alternate methods of analysis test for specific relationships (e.g., linear, quadratic, or cubic) among variables. For more information on data analysis, please see the NCES Statistical Standards, Standard 5-1, available at http://nces.ed.gov/statprog/2002/std5_1.asp. A number of considerations influence the ultimate selection of the data years to feature in The Condition of Education. To make analyses as timely as possible, the latest year of available data is shown. The choice of comparison years is often also based on the need to show the earliest available survey year, as in the case of the NAEP and the international assessment surveys. In the case of surveys with long time frames, such as surveys measuring enrollment, the decade’s beginning year (e.g., 1980 or 1990) often starts the trend line. In the figures and tables of the indicators, intervening years are selected in increments in order to show the general trend. The narrative for the indicators typically compares the most current year’s data with those from the initial year and then with those from a more recent period. Where applicable, the narrative may also note years in which the data begin to diverge from previous trends.
Rounding and Other Considerations
All calculations within The Condition of Education are based on unrounded estimates. Therefore, the reader may find that a calculation, such as a difference or a percentage change, cited in the text or figure may not be identical to the calculation obtained by using the rounded values shown in the accompanying tables. Although values reported in the supplemental tables are generally rounded to one decimal place (e.g., 76.5 percent), values reported in each indicator are generally rounded to whole numbers (with any value of 0.50 or above rounded to the next highest whole number). Due to rounding, cumulative percentages may sometimes equal 99 or 101 percent rather than 100 percent. Indicators in this volume that use the Consumer Price Index (CPI) use a base academic year of 2010–11 and a base calendar year of 2011 for constant dollar calculations. For more information on the CPI, see Appendix C – Finances.
Race and ethnicity
The categories denoting race and ethnicity in The Condition of Education are in accordance with the 1997 Office of Management and Budget (OMB) standard classification scheme. These classifications are based primarily on the respondent’s self-identification, as is the case with data collected by the U.S. Census Bureau, or, in rare instances, on observer identification. Under the OMB standards, race and ethnicity are considered separate concepts. “Hispanic or Latino” is an ethnicity category, not a race category. Race categories presented in The Condition of Education 2012 exclude persons of Hispanic ethnicity; thus, the race/ethnicity categories are mutually exclusive.
Ethnicity is categorized as follows:
In The Condition of Education, the following terms are typically used to represent the above categories: White, Black, Hispanic, Pacific Islander, American Indian/Alaska Native, and Two or more races. Not all categories are shown in all indicators. For more information on race/ ethnicity, see Appendix C – Commonly Used Measures.
Symbols
In accordance with the NCES Statistical Standards, many tables in this volume use a series of symbols to alert the reader to special statistical notes. These symbols, and their meanings, are as follows:
— Not available.
† Not applicable.
# Rounds to zero.
! Interpret data with caution. The coefficient of variation (CV) for this estimate is 30 percent or greater.
‡ Reporting standards not met. Either there are too few cases or the coefficient of variation (CV) for this estimate is 50 percent or greater.
* p < .05 Significance level.
