National Drug Abuse Treatment System Survey, Waves II-IV (ICPSR 4146)

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Date of Collection View help for Date of Collection

Data Collection Notes View help for Data Collection Notes

Study Purpose View help for Study Purpose

To understand the organizational determinants of treatment practices in a national sample of substance abuse treatment units.

Study Design View help for Study Design

Stratified Random Sample

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Though Wave I is not a part of this public release, its sample design is relevant due to the longitudinal design of the study. A stratified random sample of n = 413 outpatient drug treatment units were selected. The sample was selected from national databases of federally supported treatment programs and was restricted to outpatient drug treatment programs that were drug-free (i.e., they did not use methadone or related treatments). Alcohol treatment programs were excluded. The primary stratification criteria included: location (inner city, suburban, rural), funding agency (National Institute of Mental Health (NIMH) or National Institute on Drug Abuse (NIDA)), and program classification (freestanding versus those based in a community mental health clinic (CMHC)).

Wave II: As mentioned previously, the survey population for Wave II was expanded to include methadone-based treatment programs. The Survey Research Center's (SRC) sampling section developed a comprehensive national frame of approximately 8,149 program listings to meet the expanded sample requirements. The primary stratification criteria of the National Sample Frame of Drug Treatment Programs (NSFDTP) had: public versus private program, methadone versus drug-free treatment, and program type (CMHC, hospital, or freestanding). After selecting a stratified random sample, screening for eligibility, and selecting a stratified subsample, 438 programs were chosen for inclusion in the survey. In addition to these programs, an additional 207 programs from Wave I were deemed to be eligible programs and were added as a recontact sample, A total of 575 programs provided a program director interview, a clinical supervisor interview, or both.

Wave III: No sample of new programs was included in Wave III, which was a longitudinal follow-up of the programs that were successfully interviewed in Wave II. In Wave III, 550 programs were found to be still operating and eligible, and 481 total programs provided a program director interview, a clinical supervisor interview, or both.

Wave IV: This wave included both a longitudinal sample of those programs that completed waves II and III, and was also supplemented with a new stratified random sample from a completely updated National Frame of Substance Abuse Treatment Programs (NFSATP).

Interviews were attempted with the 429 programs that participated in Waves II and III, and were also still operating and eligible. In Wave IV, 387 of these programs provided a program director interview, a clinical supervisor interview, or both.

The sample frame for the new supplemental cross sectional sample is a subset of the NFSATP. The full NFSATP database is the integration of four drug treatment program databases:

• National Facilities Register (NFR), 1992 NDATUS (a predecessor to the National Survey of Substance Abuse Treatment Services, N-SSATS) -- provided to the SRC by the Substance Abuse and Mental Health Services Administration (SAMHSA).
• The 1994 American Hospital Association (AHA) Survey -- added to ensure comprehensive coverage of hospital-based programs.
• 1994 Food and Drug Admisistration (FDA) List of Licensed Methadone Treatment Programs -- printed list provided to SRC by the FDA at the request of SAMHSA.
• The Survey Sampling, Inc. (SSI) Business Data Base -- purchased in order to ensure comprehensive coverage of privately operated programs.

The Wave IV sample was assigned to 12 stratum codes as defined by the same primary stratification criteria as existed for the Wave II sample (public vs. private program, methadone vs. drug-free treatment, and program -- CMHC, hospital, or freestanding). However, the database components of the NFSATP did not always supply all the necessary information needed to classify each program to one of the 12 strata. These programs with incomplete information for stratum assignments were, as a rule, included in the private, nonhospital, nonmethadone stratum.

It was determined that the outpatient drug treatment program sector that had experienced the most growth correlated with the private, nonhospital, nonmethadone stratum. Thus it was decided that the supplemental sample would be a subsample of the NFSATP programs that were known to be private, nonhospital, nonmethadone programs or for which there was incomplete information for proper classification into one of the 12 stratum as described above. After initial screening of this subsample for eligibility, 270 programs were determined to be eligible for interviews. Of these, 231 total programs provided a program director interview, a clinical supervisor interview, or both. Based on the more complete information gathered from the interviews, 81 programs were reclassified into one of the other 11 stratum.

Universe View help for Universe

Outpatient Drug Abuse Units in the United States

Unit(s) of Observation View help for Unit(s) of Observation

Data Type(s) View help for Data Type(s)

Mode of Data Collection View help for Mode of Data Collection

Description of Variables View help for Description of Variables

The data include variables from the following major areas of investigation: referral sources, client demographics, types of problems treated, unit staffing, diagnostic and assessment patterns, treatment goals, services provided, end-of-treatment outcomes, quality improvement efforts, funding, licensing and accreditation, collaboration and competition with other treatment organizations, and recent programmatic changes.

Response Rates View help for Response Rates

1988: 86 percent

1990: 88 percent

1995: 87 percent

Original Release Date View help for Original Release Date

2009-07-30

Version History View help for Version History

Weight View help for Weight

Each of the three data files come with two weight variables, a trimmed weight and a centered weight. Both of these weight variables are derived from an original weight variable (not included in the public data file). For each wave of the data, the original weight variable was produced by the principal investigator in order to reduce bias, which may be associated with unequal sample selection probabilities and nonresponse. Trimmed and centered weights are defined as follows:

Trimmed Weight: One disadvantage of weighting to decrease bias is that it might increase the variance of weighted estimates. When it appears that a few weights are disproportionately affecting the variance, then outlier weights are often trimmed. With trimming it is implicitly assumed that the potential increase in bias is small relative to the reduction in variance. The ultimate goal of weight trimming is to reduce the sampling variance more than enough to compensate for the possible increase in bias and, thereby, to reduce the mean squared error. For this study, the trimming consisted of reducing outlier weights to a value slightly larger than the next largest value within the same stratum. To maintain the total sum of all weight values, the excess "trimmed" weight was then redistributed to the other weight values within the same stratum.

Centered Weight: When a typical weight is applied, the weighted estimates are inflated to the full population value from which the sample was drawn. This results in standard errors that are inappropriately deflated. Centered weights are commonly used to avoid this problem. The centered weights for this study are calculated by taking the trimmed weight for each case and dividing by the mean of the trimmed weight variable.