Morbidity and Mortality Weekly Report: Summary of Notifiable Diseases
The Summary of Notifiable Diseases, a publication of the Morbidity and Mortality Weekly Report (MMWR), contains the official statistics, in tabular and graphical form, for the reported occurrence of nationally notifiable infectious diseases in the United States. These statistics are collected and compiled from reports sent by U.S. state and territory, New York City, and District of Columbia health departments to the National Notifiable Diseases Surveillance System (NNDSS), which is operated by the Centers for Disease Control and Prevention (CDC) in collaboration with the Council of State and Territorial Epidemiologists.
For more information on the MMWR: Summary of Notifiable Diseases, see https://www.cdc.gov/mmwr/mmwr_nd/ .
National Vital Statistics System
The National Vital Statistics System (NVSS) is the method by which data on vital events—births, deaths, marriages, divorces, and fetal deaths—are provided to the National Center for Health Statistics (NCHS), part of the Centers for Disease Control and Prevention (CDC). The data are provided to NCHS through the Vital Statistics Cooperative Program (VSCP). Detailed mortality data from NVSS are accessed through CDC’s Wide-ranging Online Data for Epidemiologic Research (WONDER), providing the counts of homicides among youth ages 5–18 and suicides among youth ages 10–18 by school year (i.e., from July 1 through June 30). These counts are used to estimate the proportion of all youth homicides and suicides that are school associated in a given school year.
For more information on the NCHS and the NVSS, see https://www.cdc.gov/nchs/nvss/index.htm.
School-Associated Violent Death Surveillance System
The School-Associated Violent Death Surveillance System (SAVD-SS) was developed by the Centers for Disease Control and Prevention (CDC) in conjunction with the U.S. Department of Education and the U.S. Department of Justice. The system contains descriptive data on all school-associated violent deaths in the United States, including homicides, suicides, and legal intervention deaths where the fatal injury occurred on the campus of a functioning elementary or secondary school; while the victim was on the way to or from regular sessions at such a school; or while attending or on the way to or from an official school-sponsored event. Victims of such incidents include students as well as nonstudents (e.g., students’ parents, community residents, and school staff). SAVD-SS includes data on the school, event, victim(s), and offender(s). These data are used to describe the epidemiology of school-associated violent deaths, identify common features of these deaths, estimate the rate of school-associated violent deaths in the United States, and identify potential risk factors for these deaths. The CDC has collected SAVD-SS data from July 1, 1992, to the present.
SAVD-SS uses a three-step process to identify and collect data on school-associated violent deaths. First, cases are identified through a systematic search of the LexisNexis newspaper and media database. Second, law enforcement officials from the office that investigated the death(s) are contacted to confirm the details of the case and to determine if the event meets the case definition. Third, once a case is confirmed, a copy of the full law enforcement report is requested for each case. Finally, in previous data years whenever possible, interviews were conducted with law enforcement and/or school officials familiar with cases to obtain contextual information about the incidents. However, interviews are no longer conducted as a part of SAVD-SS protocol. Information regarding the fatal incident is abstracted from law enforcement reports and includes the location of injury, context of injury (while classes were being held, during break, etc.), motives for injury, method of injury, and relationship, school, and community circumstances that may have been related to the incident (e.g., relationship problems with family members, school disciplinary issues, gang-related activity in the community). Information obtained on victim(s) and offender(s) includes demographics, contextual information about the event (date/time, alcohol or drug use, number of persons involved), types and origins of weapons, criminal history, psychological risk factors, school-related problems, extracurricular activities, and family history, including structure and stressors. For specific SAVD studies, school-level data for schools where incidents occur are obtained through the Common Core of Data survey of the National Center for Education Statistics and include school demographics, locale (e.g., urban, suburban, rural), grade levels offered by the school, Title I eligibility, and percentage of students eligible for free/reduced-price lunch, among other variables.
All data years are flagged as preliminary. For some recent cases, the law enforcement reports have not yet been received. The details learned during data abstraction from law enforcement reports can occasionally change the classification of a case. Also, new cases may be identified because of the expansion of the scope of the media files used for case identification or as a result of newly published media articles describing the incident. Finally, other cases may occasionally be identified while the law enforcement and school interviews are being conducted to verify known cases.
Further information on SAVD-SS may be obtained from
Ruth Leemis, M.P.H.
Principal Investigator and Behavioral Scientist
School-Associated Violent Death Surveillance System
Division of Violence Prevention
National Center for Injury Control and Prevention
Centers for Disease Control and Prevention
770-488-0681
xbf2@cdc.gov
Web-Based Injury Statistics Query and Reporting System Fatal
Web-Based Injury Statistics Query and Reporting System (WISQARS) Fatal is an interactive online database that provides mortality data related to injury. The mortality data reported in WISQARS Fatal come from death certificate data reported to the National Center for Health Statistics (NCHS), Centers for Disease Control and Prevention (CDC). Data include causes of death reported by attending physicians, medical examiners, and coroners and demographic information about decedents reported by funeral directors, who obtain that information from family members and other informants. NCHS collects, compiles, verifies, and prepares these data for release to the public. The data provide information about unintentional injury, homicide, and suicide as leading causes of death, how common these causes of death are, and whom they affect. These data are intended for a broad audience—the public, the media, public health practitioners and researchers, and public health officials—to increase their knowledge of injury.
WISQARS Fatal mortality reports provide tables of the total numbers of injury-related deaths and the death rates per 100,000 U.S. population. The reports list deaths according to cause (mechanism) and intent (manner) of injury by state, race, Hispanic origin, sex, and age groupings.
Further information on WISQARS Fatal may be obtained from
National Center for Injury Prevention and Control
Centers for Disease Control and Prevention
1600 Clifton Road
Atlanta, GA 30329
https://wwwn.cdc.gov/dcs/ContactUs/Form
https://www.cdc.gov/injury/wisqars/fatal_help/data_sources.html
Youth Risk Behavior Surveillance System
The Youth Risk Behavior Surveillance System (YRBSS) is an epidemiological surveillance system developed by the Centers for Disease Control and Prevention (CDC) to monitor the prevalence of youth behaviors that most influence health. The YRBSS focuses on priority health-risk behaviors established during youth that result in the most significant mortality, morbidity, disability, and social problems during both youth and adulthood. The YRBSS includes a national school-based Youth Risk Behavior Survey (YRBS), as well as surveys conducted in states, territories, tribes, and local school districts.
The national YRBS uses a three-stage cluster sampling design to produce a nationally representative sample of students in grades 9–12 in the United States. In each survey, the target population consisted of all public and private school students in grades 9–12 in the 50 states and the District of Columbia. The first-stage sampling frame included selecting primary sampling units (PSUs) from strata formed on the basis of urbanization and the relative percentage of Black and Hispanic students in the PSU. These PSUs are either counties; subareas of large counties; or groups of smaller, adjacent counties. At the second stage, schools were selected with probability proportional to school enrollment size.
The final stage of sampling consisted of randomly selecting, in each chosen school and in each of grades 9–12, one or two classrooms from either a required subject, such as English or social studies, or a required period, such as homeroom or second period. All students in selected classes are eligible to participate. In surveys conducted before 2013, three strategies were used to oversample Black and Hispanic students: (1) larger sampling rates were used to select PSUs that are in high-Black and high-Hispanic strata; (2) a modified measure of size was used that increased the probability of selecting schools with a disproportionately high minority enrollment; and (3) two classes per grade, rather than one, were selected in schools with a high percentage of Black or Hispanic enrollment. In 2013, 2015, 2017, and 2019, only selection of two classes per grade was needed to achieve an adequate precision with minimum variance. Approximately 16,300 students participated in the 1993 survey; 10,900 students participated in 1995; 16,300 students participated in 1997; 15,300 students participated in 1999; 13,600 students participated in 2001; 15,200 students participated in 2003; 13,900 participated in 2005; 14,000 participated in 2007; 16,400 participated in 2009; 15,400 participated in 2011; 13,600 participated in 2013; 15,600 participated in 2015, 14,800 participated in 2017; and 13,700 participated in 2019.
The overall response rate was 70 percent for the 1993 survey; 60 percent for the 1995 survey; 69 percent for the 1997 survey; 66 percent for 1999; 63 percent for 2001; 67 percent for 2003 and 2005; 68 percent for 2007; 71 percent for 2009 and 2011; 68 percent for 2013; and 60 percent for 2015, 2017, and 2019. NCES standards call for response rates of 85 percent or better for cross-sectional surveys, and bias analyses are required by NCES when that percentage is not achieved. Because of data limitations, however, a full nonresponse bias analysis has not been done for the YRBS. For YRBS data, a full nonresponse bias analysis has not been done because the data necessary to do the analysis are not available (e.g., differences between participating and non-participating students cannot be measured, because no survey data are available from non-participating students). A school nonresponse bias analysis, however, was done for the 2019 survey. This analysis found some evidence of potential bias by school urbanicity and school affluence, but concluded that the bias was unlikely to have impacted the national estimates in a meaningful way and would be further reduced by weight adjustment. The weights were developed to adjust for nonresponse and the oversampling of Black and Hispanic students in the sample. The final weights were constructed so that only weighted proportions of students (not weighted counts of students) in each grade matched national population projections.
State-level data were downloaded from the Youth Online: Comprehensive Results web page (https://nccd.cdc.gov/Youthonline/App/Default.aspx). Each state and district school-based YRBS employs a two-stage, cluster sample design to produce representative samples of students in grades 9–12 in their jurisdiction. In 2019, all state and district samples include only public schools, and each district sample includes only schools in the funded school district (e.g., San Diego Unified School District) rather than in the entire city (e.g., greater San Diego area).
In the first sampling stage in all except a few states and districts, schools are selected with probability proportional to school enrollment size. In the second sampling stage, intact classes of a required subject or intact classes during a required period (e.g., second period) are selected randomly. All students in sampled classes are eligible to participate. Certain states and districts modify these procedures to meet their individual needs. For example, in a given state or district, all schools, rather than a sample of schools, might be selected to participate. State and local surveys that have a scientifically selected sample, appropriate documentation, and an overall response rate greater than or equal to 60 percent (or nonresponse bias analysis indicating no significant bias) are weighted. The overall response rate reflects the school response rate multiplied by the student response rate. These three criteria are used to ensure that the data from those surveys can be considered representative of students in grades 9–12 in that jurisdiction. A weight is applied to each record to adjust for student nonresponse and the distribution of students by grade, sex, and race/ethnicity in each jurisdiction. Therefore, weighted estimates are representative of all students in grades 9–12 attending schools in each jurisdiction. Surveys that do not have an overall response rate of greater than or equal to 60 percent and that do not have appropriate documentation are not weighted and are not included in this report.
In the 2019 YRBS, a total of 44 states, 28 local school districts, 3 territories, and 2 tribal governments had representative data. (For information on the location of the states, districts, territories, and tribal governments, please see https://www.cdc.gov/healthyyouth/data/yrbs/participation.htm.) In sites with representative data, the student sample sizes for the state and district YRBS ranged from 970 to 41,091. School response rates ranged from 65 to 100 percent, student response rates ranged from 56 to 92 percent, and overall response rates ranged from 40 to 92 percent.
Readers should note that reports of these data published by the CDC and in this report do not include percentages for which the denominator includes fewer than 100 unweighted cases.
In 1999, in accordance with changes to the Office of Management and Budget’s standards for the classification of federal data on race and ethnicity, the YRBS item on race/ethnicity was modified. The version of the race and ethnicity question used in 1993, 1995, and 1997 was
How do you describe yourself?
The version used in 1999, 2001, and 2003, as well as in the 2005 state and local district surveys was
How do you describe yourself? (Select one or more responses.)
In the 2005 national survey and in all 2007, 2009, 2011, 2013, 2015, 2017, and 2019 surveys, race/ethnicity was computed from two questions: (1) “Are you Hispanic or Latino?” (response options were “Yes” and “No”), and (2) “What is your race?” (response options were “American Indian or Alaska Native,” “Asian,” “Black or African American,” “Native Hawaiian or Other Pacific Islander,” or “White”). For the second question, students could select more than one response option. For this report, students were classified as “Hispanic” if they answered “Yes” to the first question, regardless of how they answered the second question. Students who answered “No” to the first question and selected more than one race/ethnicity in the second category were classified as “More than one race.” Students who answered “No” to the first question and selected only one race/ethnicity were classified as that race/ethnicity. Race/ethnicity was classified as missing for students who did not answer the first question and for students who answered “No” to the first question but did not answer the second question.
CDC has conducted two studies to understand the effect of changing the race/ethnicity item on the YRBS. Brener, Kann, and McManus (Public Opinion Quarterly, 67:227–226, 2003) found that allowing students to select more than one response to a single race/ethnicity question on the YRBS had only a minimal effect on reported race/ethnicity among high school students. Eaton, Brener, Kann, and Pittman (Journal of Adolescent Health, 41: 488–494, 2007) found that self-reported race/ethnicity was similar regardless of whether the single-question or a two-question format was used.
Further information on the YRBSS may be obtained from
Nancy Brener
Division of Adolescent and School Health
National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention
Centers for Disease Control and Prevention
1600 Clifton Road
Atlanta, GA 30329
nad1@cdc.gov
http://www.cdc.gov/yrbs