mental health services,
substance abuse treatment,
Date of Collection:
Unit of Observation:
The civilian, noninstitutionalized population of the
United States aged 12 and older, including residents of
noninstitutional group quarters, such as college dormitories, group
homes, shelters, rooming houses, and civilians dwelling on military
Data Collection Notes:
Data were collected by Research Triangle
Institute, Research Triangle Park, NC, and prepared for release by
National Opinion Research Center, Chicago, IL.
Household Survey on Drug Abuse questionnaire and estimation
methodology changed with the implementation of the 1994-B
survey. Therefore, estimates produced from the 1995 survey are not
comparable to those produced from the 1994-A and earlier surveys.
For selected variables, statistical imputation was performed following
logical imputation to replace missing responses. These variables are
identified in the codebook as "...LOGICALLY IMPUTED" and
"...imputed" for the logical procedure or by the designation
"IMPUTATION-REVISED" in the variable label when the statistical
procedure was also performed. The names of statistically imputed
variables begin with the letters "IR". For each imputation-revised
variable there is a corresponding imputation indicator variable that
indicates whether a case's value on the variable resulted from an
interview response or was imputed by the hot-deck technique. Hot-deck
imputation is described in the codebook.
The "basic sampling
weights" are equal to the inverse of the probabilities of selection
of sample respondents. To obtain "final NHSDA weights," the basic
weights were adjusted to take into account dwelling unit-level and
individual-level nonresponse and further adjusted to ensure
consistency with intercensal population projections from the United
States Bureau of the Census.
To protect the confidentiality of
respondents, all variables that could be used to identify individuals
have been encrypted or collapsed in the public use file. These
modifications should not affect analytic uses of the public use
Users who wish to replicate results published in the NHSDA
Main Findings Report or other SAMHSA reports should use the 1995 NHSDA
imputed data for prevalence estimates rather than raw data from the
questionnaire or drug answer sheets.
Family and personal income
range variables were constructed from two imputation-revised variables
that were deleted from the public use dataset and codebook due to
confidentiality issues. Users are advised that the recoded income
range variables cannot be replicated from the imputation-revised
variables (IRFINC1 and IRPINC1) contained in the public use file.
For some drugs that have multiple names, questions regarding the use of that drug may be asked for each distinct name. For example, even though methamphetamine, methedrine and desoxyn are the same drug, their use was measured in three separate variables.
Multistage area probability sample design involving five
selection stages: (1) primary sampling units areas (e.g., counties), (2) subareas within primary areas (e.g., blocks or block groups), (3) listing units within subareas, (4) age-group-smoking classes within sampled listing units, and (5) eligible individuals within sampled age-group-smoking classes. A total of 115 Primary Sampling Units (PSUs), including areas of high Hispanic concentration, were selected to represent the total United States population. These PSUs were defined as metropolitan areas, counties, groups of counties, and independent cities. Of the 115 PSUs, 43 were selected with certainty and 72 were randomly selected with probability proportional to size. Based on correlations between past-month cigarette smoking and
drug use, cigarette smokers were oversampled to increase the precision of drug use estimates. The four age groups were: ages 12-17, 18-34, 35-49, and 50 and older. The three race/ethnic groups were: Whites/others, Blacks, and Hispanics. Blacks and Hispanics were oversampled. The age-group-smoking selection probabilities were based
on the desired sample sizes for each age group by racial/ethnic domain. The probabilities of selecting the person within the age-group-smoking domain were based on the number of persons found in the age-smoking group. The study yielded an 85.0 percent eligibility rate for sample households and a 94.2 percent completion rate for screening
Data were weighted based on the
five stages of sampling that were used. Adjustments were made to compensate for nonresponse and
sampling error. Adjustments also included trimming sample weights to
reduce excessive weight variation and a post-stratification to Census
population estimates. The final weight variable to be used in analysis is ANALWT.
personal interviews and self-enumerated answer sheets
The interview response rates for the three racial/ethnic groups were: 79.6 percent for Whites/others, 80 percent for Blacks, and 83.2 percent for Hispanics. The overall unweighted interview response rate was 80.6 percent. A completed interview had to contain, at a minimum, data on the recency of use of marijuana, cocaine, and alcohol.
Extent of Processing: ICPSR data undergo a confidentiality review and are altered when necessary to limit the risk of
disclosure. ICPSR also routinely creates ready-to-go data files along with setups in the major
statistical software formats as well as standard codebooks to accompany the data. In addition to
these procedures, ICPSR performed the following processing steps for this data collection:
Performed consistency checks.
Standardized missing values.
Created online analysis version with question text.
Checked for undocumented or out-of-range codes.
Restrictions: Users are reminded by the United States Department of Health and Human Services that these data are to be used solely for statistical analysis and reporting of aggregated information and not for the investigation of specific individuals or treatment facilities.