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2002 State Estimates of Substance Use

1. Introduction

This report presents State estimates for 20 measures of substance use or mental health problems based on the 2002 National Survey on Drug Use and Health (NSDUH).1 Sponsored by the Substance Abuse and Mental Health Administration (SAMHSA), NSDUH is an ongoing survey of the civilian, noninstitutionalized population of the United States aged 12 years old or older. Approximately 68,000 persons were interviewed in 2002. State estimates presented in this report are based on data collected in 2002 and have been developed using a small area estimation (SAE) procedure in which State-level NSDUH data are combined with local-area county and census block group/tract-level data from the State. These model-based estimates provide more precise estimates of substance use at the State level than estimates based solely on the sample.

Beginning with the 1999 survey data, SAMHSA produced estimates at the State level for a selected set of variables (Office of Applied Studies [OAS], 2001b). These variables included prevalence rates for a number of licit and illicit substances, perceptions of risks of substance use, and other measures related to substance dependence and abuse. In 2000, 12 of the same measures were repeated in the questionnaire, and a modified set of questions related to substance dependence and abuse was added. These new questions capture more accurately and completely information on dependence and abuse criteria described in the 4th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) (American Psychiatric Association [APA], 1994). For the report of the 2000 State estimates, the 12 measures that were common to 1999 and 2000 had their estimates based on the combined data for those years in order to improve their accuracy (Wright, 2002a, 2002b).

In 2001, a measure for serious mental illness (SMI) was added to the questionnaire, expanding the number of measures estimated at the State level to 19. The other 18 measures were based on combined data for 2000 and 2001. In 2002, incentive payments of $30 were given to respondents for the first time in order to address concerns about the national and State response rates. The name of the survey was changed. Other changes included new data collection quality control procedures and a shift from the 1990 decennial census to the 2000 census as a basis for population count totals and to calculate any census-related prediction variables that are used in the estimation. These changes and others improved the quality of the data provided by the survey, with the most notable result being the increase in interview response rates from 73.3 percent in 2001 (Table E.20, Wright, 2003b) to 78.6 percent in 2002 (Table B.3).

However, an unanticipated result was that the prevalence rates for 2002 were in general substantially higher than those for 2001—substantially higher than could be attributable to the usual year-to-year trend—and thus are not comparable with estimates for 2001 and prior years.2 Therefore, the 2002 NSDUH represents a new baseline for the State, as well as national, estimates. Given the varying effects of the incentive and other changes on the States, not only are the estimates not comparable with prior years, but even the relative rankings of States may have been affected. Therefore, the rankings of States for 2002 should not be compared with those for prior years. With 2002 as a new State baseline, the 2002 State estimates are only based on a single year's data and, as a result, are somewhat less precise than the 2001 estimates, which were based on combined data for 2000 and 2001.

Because the SAE methodology is essentially the same as that reflected in the 2001 State report, the 2002 NSDUH State report has been reduced to a single volume that covers the prevalence rates and a discussion of results. For information on the quality of the estimates, see Chapter 7 of this report. For a description of refinements made in the 2002 SAE methodology relative to prior years, see Appendix B. Also included in that appendix are the State sample sizes and response rates for 2000–2001 and 2002 (Tables B.1 to B.4). For a more detailed discussion of the SAE methodology, see Appendix E of the 2001 State report (Wright, 2003b). Tables of model-based estimates for each substance use or mental health measure are included in Appendix A. Additional tables showing the corresponding estimated total number of persons for each measure (see and individual State tables listing all 20 measures (see are provided on the SAMHSA website.


1.1. Prior Releases of State Estimates

The Summary of Findings from the 1999 NHSDA (OAS, 2000) presented national estimates of substance use and, for the first time, State estimates for seven priority variables for all persons aged 12 or older and three age groups (12 to 17, 18 to 25, and 26 or older). Subsequently, 1999 State estimates were developed for additional substance use measures for the same age groups (OAS, 2002a). In total, there were 18 measures reported. These results and all subsequent State and national estimates have been posted to the SAMHSA website.

A special State report that focused on youths (also based on the 1999 NHSDA) was released in 2001 (Wright & Davis, 2001). In 2000 and 2001, the national results were released separately (OAS, 2001c, 2002b, 2002c) from the State results. State estimates for 2000 were released in two volumes, one with the findings and the other with the technical appendices (Wright, 2002a, 2002b). National and State estimates of the drug abuse treatment gap for 2000 appeared in a separate report (OAS, 2002d). State estimates for the 2001 NHSDA also were released in two volumes, one with findings and the other with technical appendices (Wright, 2003a, 2003b).


1.2. Summary of NSDUH Methodology

NSDUH is the primary source of statistical information on the use of illicit drugs by the U.S. civilian population aged 12 or older. Conducted by the Federal Government since 1971, the survey collects data by administering questionnaires to a representative sample of the population through face-to-face interviews at their place of residence. The survey is planned and managed by SAMHSA's OAS, and the data are collected and processed by RTI International.3 This section briefly describes the national survey methodology. A more complete description is provided in Appendix B of the 2002 national findings report (OAS, 2003b).

The survey covers residents of households, noninstitutional group quarters (e.g., shelters, rooming houses, dormitories), and civilians living on military bases. Persons excluded from the survey include homeless people who do not use shelters, active military personnel, and residents of institutional group quarters, such as prisons and long-term hospitals. The 1999 NHSDA marked the first survey year in which the national sample was interviewed using a computer-assisted interviewing (CAI) method. The survey used a combination of computer-assisted personal interviewing (CAPI) conducted by an interviewer and audio computer-assisted self-interviewing (ACASI). Use of ACASI is designed to provide the respondent with a highly private and confidential means of responding to questions and should increase the level of honest reporting of illicit drug use and other sensitive behaviors. For further details on the development of the CAI procedures for the 1999 NHSDA, see OAS (2001a).

The 1999 through 2001 NHSDAs and the 2002 NSDUH employed a 50–State design with an independent, multistage area probability sample for each of the 50 States and the District of Columbia. The eight States with the largest population (which together accounted for 48 percent of the total U.S. population aged 12 or older) were designated as large sample States (California, Florida, Illinois, Michigan, New York, Ohio, Pennsylvania, and Texas). Collectively, the sample allocated to these States ensured adequate precision at the national level while providing individual State samples large enough to support both model-based (SAE) and design-based estimates. For the remaining 42 States and the District of Columbia, smaller, but adequate, samples were selected to support State estimates using SAE techniques (described in Appendix E of the 2001 State report, Wright, 2003b). The design also oversampled youths and young adults, so that each State's sample was approximately equally distributed among three major age groups: 12 to 17 years, 18 to 25 years, and 26 years or older.

Nationally, 136,349 addresses were screened and 68,126 persons were interviewed within the screened addresses. The 2002 survey was conducted from January through December 2002. The screening response rate for 2002 was 90.7 percent, and the interviewing response rate was 78.6 percent, obtaining an overall response rate of 71.3 percent (compared with an overall response rate of 67.3 percent in 2001 [Table E.20, Wright, 2003b]). In 2002, the overall State response rates ranged from 60.9 to 83.1 percent (see Table B.3).

Estimates in this report have been adjusted to reflect the probability of selection, unit nonresponse, poststratification to known benchmarks, item imputation, and other aspects of the estimation process.


1.3. Format of Report and Presentation of Data

The findings presented in this report are divided into seven chapters, including this introductory chapter, along with U.S. maps at the ends of Chapters 2 through 6, and data tables in Appendix A at the end of the report.

Chapter 2 presents State estimates of marijuana use, incidence of marijuana use, perceived risks of marijuana use, any illicit drug use, any illicit drug use other than marijuana, and cocaine use. Chapter 3 discusses analogous estimates of alcohol use, binge alcohol use, and the perceived risks of binge alcohol use. Chapter 4 presents estimates for tobacco use, cigarette use, and the perceptions of risk of heavy cigarette use. Chapter 5 discusses the substance treatment–related measures (i.e., dependence on and abuse of illicit drugs or alcohol). Chapter 6 presents estimates of serious mental illness (SMI). Chapter 7 is a discussion of the findings.

At the ends of Chapters 2 to 6, State model-based estimates are portrayed in U.S. maps showing all 50 States and the District of Columbia. The maps reflect the ranking of States into fifths from lowest to highest to simplify the discussion in the chapters. The quintile rankings can be determined from tables that include all 50 States and the District of Columbia, listed in alphabetical order (Appendix A), by four age categories. Appendix B gives a brief description of the SAE methodology and discusses minor refinements in that methodology relative to prior years. Individual State tables also are available on the SAMHSA website to display all of the estimates discussed in this report by the four age categories for a given State (see Corresponding to the estimated percentages or rates for each substance use or mental health measure in Appendix A are tables of the total number of persons associated with each measure. These estimates are available at the same website location.

The color of each State on the U.S. maps indicates how the State ranks relative to other States for each measure. States could fall into one of five groups according to their ranking by quintiles. Because there are 51 areas to be ranked, the middle quintile was assigned 11 areas and the remaining groups 10 each. In some cases, a "quintile" could have more or fewer States than desired because two (or more) States have the same estimate (to two decimal places). When this occurs at the "boundary" between two "quintiles," all States with the same estimate were assigned to the lower quintile. Those States with the highest rates for a given variable are in red, with the exception of the perceptions of risk variables, for which the lowest perceptions of great risk are in red. Those States with the lowest estimates are in white, with the exception of the perceptions of risk variables, for which the highest perceptions of great risk are in white.

At the top of each table in Appendix A is a national total that represents the (weighted) sum of the estimates from the 50 States and the District of Columbia. In 2002, those totals have been benchmarked for the first time in order to agree with the corresponding national estimates calculated by summing the sample-weighted records across the entire sample (reflected in the 2002 national report). (For more details, refer to Appendix B, Section B.4.)

Associated with each State estimate is a 95 percent prediction interval (PI). These intervals indicate the precision of the estimate. For example, the State with the highest estimated past month alcohol rate for youths (a model-based estimate) was North Dakota, with a rate of 24.7 percent (Table A.7). The 95 percent PI on that estimate is from 20.7 to 29.1 percent. Therefore, the probability is 0.95 that the true prevalence for North Dakota will fall between 20.7 and 29.1 percent. The PI indicates the uncertainty due to both sampling variability and model bias.


1.4. Measures Presented in This Report

Estimates based on the 2002 NSDUH data were developed for 20 measures:


1.5. Other NSDUH Reports and Products

The national results from the 2002 survey were released in September 2003 (OAS, 2003a, 2003b). Analytic reports based on NSDUH data and focusing on specific issues or population groups also are produced by OAS. Reports in progress or recently published focus on the following topics:

A complete listing of previously published reports from this survey and other data sources is available from OAS, and many of these reports also are available through the Internet (see Electronic Access to Publication). In addition, OAS makes public use data files available to researchers through the Substance Abuse and Mental Health Data Archive (SAMHDA, 2004). Currently, files are available from the 1979 through the 2001 NHSDAs and the 2002 NSDUH.

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This page was last updated on June 03, 2008.