2002 NSDUH Data Collection Final Report

6. DATA COLLECTION

This chapter presents the basic data collection procedures given to field staff working on the 2002 NSDUH. For further details or specific instructions, consult the 2002 NSDUH Field Interviewer Manual.

6.1 Contacting Dwelling Units

Interviewers were assigned specific sample dwelling units (SDUs) to contact with the addresses or unit/location descriptions displayed on the Newton handheld computer. The sample was released in partitions, with additional units made available as needed depending on progress during the initial weeks of data collection each quarter.

6.1.1 Lead Letter

Initial contact with residents of the specific SDUs was made through a lead letter which gave a brief explanation of the nature of the study and its methods. The letter was printed on Public Health Service (PHS)/Department of Health and Human Services (DHHS) letterhead and signed by both the SAMHSA Assistant Project Officer and the RTI National Field Director.

For all SDUs with a complete address (i.e., not a location description), prepared letters preprinted with the addresses were included with the assignment materials distributed to FIs each quarter. Interviewers reviewed all addresses to check that they could be mailed, signed the letters and mailed them via first class mail prior to and throughout the first part of the quarter so that the letters arrived fairly close to the time the FI expected to be in the area. Any SDUs lacking a complete mailing address were not sent a letter. To allow for these cases and other instances of delivery problems, each interviewer had extra copies to give to respondents during a personal visit. A copy of the letter, in both English and Spanish, was also included in the Showcard Booklet for reference.

6.1.2 Initial Approach

Before knocking on the door of an SDU, the FI selected the appropriate case for that specific unit on the Newton. Each FI possessed a personalized letter of authorization printed on PHS/DHHS letterhead authorizing the FI by name to work on the study, and approached the door of the SDU with his/her RTI identification badge clearly visible. The FI also carried a variety of information materials such as Question and Answer Brochures, NSDUH Highlights, and copies of newspaper articles about NSDUH.

6.1.3 Introduction/Study Description/Informed Consent

When contacting the unit, the FI asked to speak with an adult resident (18 or older) of the unit who could serve as the screening respondent. The FI introduced himself/herself and the study. As scripted on the Newton screen, during the introduction the FI mentioned the lead letter and gave the screening respondent the Study Description. The Study Description, which was also included in the Showcard Booklet for reference, explained the purpose of the data collection effort, assured the respondent that all information gathered would be handled in the strictest confidence, and estimated the time required to complete the interview. The Study Description also stated that respondents were free to withdraw from the study at any time. Therefore, the Study Description provided all required aspects of Informed Consent for both the screening and interviewing portions of the study¹.

6.1.4 Callbacks

If no respondent was available or another situation was found at the unit so that screening could not be completed during the first visit, a minimum of four callbacks was made to the unit so that each SDU was visited at least five times in an effort to complete the screening. These contacts were made at different hours on different days of the week to increase the likelihood of completing the screening.

6.2 Dwelling Unit Screening

Screening was performed at each SDU by obtaining information about the residents of the unit to determine whether or not any household member would be eligible for the NSDUH interview based on the ages of the SDU members. The screening program guided the FIs through the process of asking age, gender, race/ethnicity, and military status for all persons aged 12 and older who lived at the unit for most of the calendar quarter, and the information was entered into the Newton.

6.3 Within-Dwelling Unit Selection

Once the roster information was entered and verified, the FI started the within-dwelling unit selection algorithm on the Newton by tapping the "Make Selection" button. The Newton automatically determined, based on the composition of the household roster, whether or not anyone in the unit was selected for the interview.

The system allowed for the selection of none, one, or two members of a household for an interview. Dwelling units with 12- to 17-year-olds on the roster were more likely to have persons selected for an interview. It was possible that if two household members were chosen, they could be within the same age group.

In order to identify each selected individual, the Newton displayed the person's roster number (based on the order in which household members were listed), the age, gender, and either the relationship to the householder (for housing units) or a first name (for group quarters units). Also listed on the Newton was a QuestID number, which was required to start the computerized interview on the laptop. FIs transmitted all the completed screening data contained on the Newton to RTI each evening.

6.4 Interview Administration

6.4.1 Informed Consent/Getting Started

Once the selected individual(s) were identified during screening, the FI asked to complete the interview(s) during that visit. If unavailable, the FI entered information about possible times for future contacts in the Newton Record of Calls. A minimum of four additional visits was made at different times of day/days of the week in an attempt to complete the interview.

For adults selected for the CAI interview, the FI used introductory scripts from the Showcard Booklet to introduce the study and the interview process. To meet the requirements of Informed Consent, the Study Description was provided as well. After receiving consent, the FI began the interview in a private location.

If the selected individual was aged 12-17, the FI was responsible for obtaining verbal consent from a parent or guardian before contacting the youth. The only exceptions to this rule were in certain group quarters situations, like dormitories, where such consent was unobtainable, or if the youth was an emancipated minor. A separate paragraph for parents/guardians was included in the introductory script. Once parental permission was granted, the FI approached the youth and introduced the study using the script to obtain the youth's agreement to participate. Parents were then asked to leave the interview setting to ensure the confidentiality of the youth's responses. When ready, the FI and the youth began the interview.

6.4.2 Computer Assisted Interviews (CAI)

The CAI interview began in the CAPI mode (computer-assisted personal interviewing), with the FI reading the questions from the computer screen and entering the respondent's replies into the computer. After completing the Reference Date Calendar, the FI explained to the respondent how to use the computer for the ACASI (audio computer-assisted self-interviewing) sections. Utilizing ACASI methodology for the sensitive drug use/non-use questions enhanced privacy since the respondent listened to the pre-recorded questions through the headphones and entered the responses directly into the computer. Beginning with a practice session which introduced the various computer keys used during the interview, the respondent then proceeded through the interview. Four times during the ACASI portion of the interview, the respondent was instructed to ask the interviewer for a specific picture pill card designed to aid respondent recall. When the respondent was finished with the ACASI portion, the interviewer once again took charge of the computer, asking additional demographic questions as well as health care, insurance, and income questions. During both the beginning and ending CAPI portions, showcards were utilized to assist respondents in answering the questions.

The average CAI administration times overall and for the various sections of the CAI interview by respondent age (youth 12-17 or adult 18+) and survey year (2001 and 2002) are given in Tables 6.1 through 6.31. These timing tables were calculated using audit trail data, which records responses and the time spent on each item. All available data are included in these tables: no ranges for appropriate lengths were established, so outliers are included. For example, in one case, the interviewer completed the interview but did not completely exit the case until two days later, causing an extremely high total time value. Extremely low values are usually attributed to breakoffs occurring within a section or the loss of data due to errors in data transmission. Full audit trail records do not exist for all completed interviews, as transmission errors sometimes caused part of the audit trail data to be lost, or computer processing issues occasionally meant that not all needed audit trail values were recorded.

Please note that the total number of interviews included varies between tables due to interview skip patterns and missing timing data, which may result from unresolved breakoff times. Interview sections with missing data, and any totals impacted by those sections, were not included in the analysis. Consider an example: if timing for alcohol for a particular interview was missing, then the timing data for alcohol, total ACASI, total core, and total time from that interview were excluded from the timing tables. Also note that variations in the questionnaire content between the survey years (e.g., questions added or deleted) may affect the comparability of some timing statistics. Additionally, discrepancies in sample size between 2001 and 2002 result from retaining audit trail files from 1 in every 3^rd data transmission in 2001 versus retaining all transmitted audit trail files in 2002.

6.4.3 End of Interview Procedures

After the last interview question, the interview process involved several final steps. FIs had to:

• prepare the Verification Form and ask the respondent to complete the remaining items on the form;
• have the respondent seal the completed Verification Form in a postage-paid envelope addressed to RTI;
• give the respondent the cash incentive;
• prepare the Incentive Payment Receipt, giving the appropriate copy to the respondent;
• complete the FI Observation Questions;
• enter the final result code in the Newton;
• gather all interview equipment and materials; and
• thank the respondent.

All completed Reference Date Calendars and Incentive Payment Receipts were sent weekly to the Field Supervisor. Sealed Verification Form envelopes were mailed to RTI as soon as possible. Each night FIs transmitted interview data to RTI.

6.5 Data Collection Management

Project management on this massive study can be summed up in one word: communication. For instance:

• Interviewers throughout the country reported to their Field Supervisor at least once each week to discuss production, problems encountered and possible resolutions, feedback on past work, plans for the next week, and any administrative issues.
• Field Supervisors each reported to their Regional Supervisor weekly, discussing production, costs, goals, staffing, and other administrative issues.
• Each Regional Director held a weekly meeting with his/her staff of Regional Supervisors to share project news and goals while addressing any problems within the region.
• All Regional Directors met each week with the National Field Director and the Project Director.
• All Directors and other key management staff met weekly with SAMHSA representatives.

Although the more formal meetings were held weekly, staff communicated almost constantly through the widespread use of e-mail. This management tool increased awareness of project issues by effectively passing information through the various management levels. The capability to send messages to interviewers using a one-way electronic messaging system on their project laptop computer allowed for timely sharing of information with all field staff.

With the Web-based project Case Management System, all management staff had access to a tremendous amount of information on the status of events in the field. Additional details on the CMS are provided in Section 8.2.

Another helpful management tool was the quarterly Performance Improvement Plan. At the end of each quarter of data collection, FSs developed specific plans in an effort to target particularly troublesome areas for improvement during the next quarter. Plans included the following information:

• A statement of the problem/situation to be addressed.
• A diagnosis of the problem in the past.
• Projected or desired outcomes.
• Specific efforts designed to accomplish these outcomes.

RSs assisted in the plan development and monitored the results of the plan's implementation.

6.6 Controlled Access Procedures

At times during the data collection process, interviewers had difficulty gaining access to particular SDUs. Interviewers with challenging circumstances were instructed to be observant, resourceful, and keep their supervisors informed of the situation. Additional suggestions taken from FS experience or from RTI's "Guide to Controlled Access Situations" were discussed. Talks with managers/owners generally centered on the importance of the study, SAMHSA and RTI's emphasis on confidentiality, and the right of the individuals to make a personal decision about participation. Supervisors sometimes contacted managers/owners directly to answer questions or concerns.

Due to prior efforts by staff who listed the dwelling units, many access problems were resolved readily. Listers recorded contact information and other steps followed to secure access so that interviewers could follow the same strategies or build on already-established relations. Supervisors at the listing stage used special reports on the CMS to monitor access situations; supervisors for screening and interviewing used the same reports and recorded additional information to update the reports.

For continuing problems, RTI had a system to generate individualized letters and packets of information about the project. When required, FIs and FSs provided basic information to RSs, who then requested the packets. Upon receiving the request, specialists at RTI prepared a cover letter and assembled materials to fit the situation. The packet was often sent via Federal Express to increase the importance placed on the contents and ensure timely delivery. A video which further explained the need for access was also available for inclusion in the packets. To assist in gaining access to colleges and universities, a special letter signed by the presidents of both Duke University and the University of North Carolina was available.

For persistent problem situations not resolved through FS/FI efforts or the letters/packets, "Please Call Us" letters were sent to the SDUs. Special care was taken that calls resulting from the letters were directed to the authorized RS or FS to set up an appointment so the FI could return and complete screening, or, in dire situations and with permission, screening information could be obtained by the FS or RS over the telephone.

Occasionally controlled access problems required assistance beyond the RS level so Regional Directors—and sometimes even the National Field Director—became involved.

6.7 Refusal Conversion Procedures

More often than desired, potential respondents exercised their "right to refuse to participate." The following were in place to try to prevent refusal situations:

• The 2002 Field Interviewer Manual gave specific instructions to the FIs for introducing both themselves and the study. Additionally, an entire chapter discussed "Obtaining Participation" and listed the tools available to field staff along with tips for answering questions and overcoming objections.
• During New-to-Project FI training, two sections of the guide covered details for contacting dwelling units and how to deal with reluctant respondents and difficult situations. During exercises and mock interviews, trainees were able to practice answering questions and using letters and handouts to obtain cooperation.
• During the 2–day Veteran FI training, most of one afternoon was spent discussing various ways for FIs to increase their comfort level at the door, thus increasing their confidence and ability to handle the many situations encountered in the field.
• All aspects of the NSDUH were designed to exude professionalism and thus enhance the legitimacy of the project. All materials provided to the public were developed carefully. Interviewers were instructed to always behave professionally and courteously.

In refusal situations, staff followed these steps:

• Detailed notes describing the situation were recorded in a Refusal Report on the Newton. FIs classified the refusal according to one of eight categories.
• After transmission from the Newton to RTI, the category of refusal and any notes were then available to the supervisor on the Web-based CMS. The FI and FS could then discuss the situation, with the FS suggesting additional tactics if necessary.
• Once the refusal situation was discussed, a refusal conversion letter was sent (if appropriate). On the CMS, the FS selected a specific letter based on the stage of the case (screening or interviewing), the category of the reason for the refusal (too busy, confidentiality concerns, etc.) and, for interviewing, the person to be addressed (the actual respondent or the parent of a selected youth). The FS could also delete the request for the letter (in situations where a letter would not be helpful or could not be delivered) or release the letter for automatic production and mailing. During 2002, 17,623 refusal conversion letters were mailed.
• The interviewer returned to the DU to try again with other tactics.
• Cases could be transferred to a different interviewer if necessary.
• Supervisors were available to reluctant respondents to discuss the importance of participation.

6.8 Problems Encountered

6.8.1 Size and Scope of the Project

By selecting areas throughout the entire country, many different types of situations arose that had to be resolved. With the large staff required by the size of the project, communication was vitally important yet it was challenging to ensure that tips and suggestions were consistently conveyed to all staff.

6.8.2 Interviewing Staff Attrition

The constant turnover of interviewing staff meant there were not enough interviewers to adequately cover the assignments in all areas. Once replacement staff were in place, FSs underwent the learning curve process with these new FIs rather than being able to build on experience FIs had gained in the field. The continued attrition caused FSs to spend considerable time dealing with staffing issues (recruiting, hiring, more intense supervision of new employee, etc.) and less time on appropriately managing the most difficult cases.

6.8.3 Refusals

Refusals at the screening and interview level have historically been a problem for the NSDUH (as with all national-level household surveys). The introduction in 2002 of the $30 cash incentive for selected respondents completing the interview decreased the number of refusals and increased the number of interviews conducted in one or two visits. However, interviewers still had to deal with numerous issues in an effort to obtain cooperation:

• The shifting economy meant members of selected households employed at higher level jobs were at home less and less inclined to devote the necessary time to participate. Persons employed at lower level jobs often worked several jobs so were also hard to find at home.
• A larger percentage of cases involved households with two persons selected for interview. Historically, response rates in households with two respondents are lower due to more frequent refusals by the second selected individual.
• With the use of a respondent incentive, each interviewer's workload decreased. Many experienced FIs had to resign in order to find other work with steady income. The shortage of qualified FI candidates to fill FI position openings continued. Those hired were often inexperienced.
• The sophisticated CMS allowed for increased monitoring of questionable FI activities resulting in fewer fraudulent cases being submitted.

6.8.4 Typical Data Collection Concerns

As is common in any large field data collection effort, staff encountered problems such as respondent availability, dwelling unit access (controlled or otherwise restricted), and high crime neighborhoods. Additionally, the use of escorts to increase interviewer comfort levels in unsafe areas had an impact on respondent reactions.

6.8.5 Newton

Using the Newton for electronic screening was a great use of technology, but the Newton had its drawbacks:

• It was sensitive to a variety of weather conditions (and all types were encountered).
• As it became full of data, its response time slowed down and tried respondents' patience.
• The touch-screen technology created a confidence issue for new staff who were unaccustomed to using computers.
• Concentrating on the device meant less eye contact with the respondent, which in turn made it tougher to establish good rapport.

6.8.6 CAI Patches

During the course of data collection for 2002, several problems were found with the logic programmed into the CAI instrument. Modifications were made to the programs loaded on the FI laptops using CAI patches. To receive the patch, FIs simply transmitted and the new program files were installed automatically. Only one patch was issued during the year. This end-of-February patch:

• Corrected a discrepancy in the demographic module in which 2 year old males subsequently appeared as having an age of 0 instead of 2.
• Updated the Spanish question QI24 to more closely match the English text.
• Corrected a typo in a WAV file reference in the marijuana module.

Table 6.1
2002 NSDUH Audit Trail Timing Data: Total Interview Time (Minutes) with FI Observation Module

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,606	22,941	15,309	43,012
Summary Statistics (Minutes)
Mean ()	55.0	61.1	60.3	66.5
Variance (2)	303.8	576.9	704.1	498.5
Standard Deviation ()	17.4	24.0	26.5	22.3
Quartiles
Maximum	260.9	2,415.9	1,414.7	472.7
Q3	64.2	70.1	70.0	77.0
Median	52.7	58.9	56.0	62.8
Q1	43.3	49.3	45.4	51.8
Minimum	0.3	0.1	0.1	0.1
Range	260.6	2,415.8	1,414.6	472.7
Mode	44.3	47.1	42.0	54.7
Percentiles
99%	105.1	112.6	138.6	139.3
95%	85.7	91.2	102.3	106.6
90%	76.4	82.5	87.9	93.8
10%	36.3	41.8	37.3	43.6
5%	32.6	37.8	33.1	39.2
1%	24.2	29.7	24.3	30.3
Extremes
5 Highest Values
(Highest)	260.9	2,415.9	1,414.7	472.7
	242.9	688.6	907.1	396.5
	180.1	463.6	585.1	368.4
	170.8	374.1	384.5	363.1
	163.8	302.9	311.4	295.9
5 Lowest Values
	1.8	0.3	0.3	0.1
	1.1	0.2	0.1	0.1
	0.5	0.2	0.1	0.1
	0.4	0.1	0.1	0.1
(Lowest)	0.3	0.1	0.1	0.1

Table 6.2
2002 NSDUH Audit Trail Timing Data: Introduction

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,606	22,941	15,309	43,012
Summary Statistics (Minutes)
Mean ()	3.6	5.1	4.0	5.3
Variance (2)	6.0	8.0	10.5	9.4
Standard Deviation ()	2.4	2.8	3.2	3.1
Quartiles
Maximum	39.6	63.0	108.3	114.3
Q3	4.7	6.3	5.0	6.4
Median	3.0	4.6	3.4	4.8
Q1	1.9	3.2	2.1	3.5
Minimum	0.0	0.0	0.0	0.0
Range	39.6	63.0	108.3	114.3
Mode	2.5	4.3	2.6	4.7
Percentiles
99%	11.8	14.0	14.2	15.4
95%	7.8	9.8	8.5	10.1
90%	6.5	8.3	7.0	8.4
10%	1.2	2.2	1.4	2.4
5%	1.0	1.7	1.1	1.9
1%	0.6	0.9	0.6	0.8
Extremes
5 Highest Values
(Highest)	39.6	63.0	108.3	114.3
	39.1	47.3	76.0	94.4
	31.9	45.8	75.2	77.2
	26.5	43.6	67.9	71.0
	23.1	42.7	67.3	62.5
5 Lowest Values
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
(Lowest)	0.0	0.0	0.0	0.0

Table 6.3
2002 NSDUH Audit Trail Timing Data: Total ACASI

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,586	22,873	15,262	42,886
Summary Statistics (Minutes)
Mean ()	38.5	41.5	42.4	46.0
Variance (2)	194.2	196.2	360.6	345.3
Standard Deviation ()	13.9	14.0	19.0	18.6
Quartiles
Maximum	145.7	215.5	370.3	309.8
Q3	46.4	49.3	50.9	54.7
Median	36.5	39.8	38.5	42.6
Q1	28.7	31.8	29.7	33.4
Minimum	0.0	0.0	0.1	0.0
Range	145.6	215.5	370.2	309.8
Mode	35.9	31.8	32.7	37.5
Percentiles
99%	81.2	82.7	106.7	107.3
95%	62.8	66.3	77.7	80.5
90%	56.4	59.2	65.9	69.4
10%	22.9	25.7	23.5	26.8
5%	20.1	22.5	20.2	23.3
1%	14.6	17.1	14.4	17.2
Extremes
5 Highest Values
(Highest)	145.7	215.5	370.3	309.8
	132.4	186.6	272.5	305.3
	129.2	163.1	250.8	291.5
	120.6	158.1	232.3	263.1
	120.1	143.5	192.8	223.3
5 Lowest Values
	0.2	0.2	0.2	0.1
	0.2	0.1	0.2	0.1
	0.1	0.1	0.1	0.1
	0.1	0.1	0.1	0.1
(Lowest)	0.0	0.0	0.1	0.0

Table 6.4
2002 NSDUH Audit Trail Timing Data: Tutorial Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,560	22,808	15,190	42,749
Summary Statistics (Minutes)
Mean ()	3.9	4.8	3.8	4.6
Variance (2)	3.2	3.5	4.9	5.1
Standard Deviation ()	1.8	1.9	2.2	2.2
Quartiles
Maximum	19.7	41.0	60.3	94.8
Q3	5.1	5.9	4.8	5.7
Median	3.8	4.7	3.4	4.2
Q1	2.6	3.5	2.3	3.1
Minimum	0.0	0.0	0.0	0.0
Range	19.7	41.0	60.3	94.8
Mode	2.8	5.4	2.0	3.5
Percentiles
99%	8.7	9.7	10.5	11.2
95%	6.8	7.8	7.4	8.3
90%	6.1	7.0	6.3	7.2
10%	1.8	2.5	1.5	2.3
5%	1.3	2.1	1.1	1.8
1%	0.6	1.3	0.5	1.1
Extremes
5 Highest Values
(Highest)	19.7	41.0	60.3	94.8
	16.9	40.4	40.3	79.3
	15.8	31.3	38.2	54.3
	15.4	22.4	28.1	48.0
	15.3	21.7	26.3	39.4
5 Lowest Values
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
(Lowest)	0.0	0.0	0.0	0.0

Table 6.5
2002 NSDUH Audit Trail Timing Data: Total Core Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,563	22,818	15,208	42,771
Summary Statistics (Minutes)
Mean ()	11.8	13.0	12.5	13.6
Variance (2)	32.8	35.4	47.7	46.1
Standard Deviation ()	5.7	5.9	6.9	6.8
Quartiles
Maximum	52.7	85.7	98.0	103.4
Q3	15.0	16.5	15.3	16.7
Median	10.8	12.1	10.9	12.2
Q1	7.6	8.7	7.9	8.9
Minimum	0.0	0.0	0.0	0.0
Range	52.7	85.7	98.0	103.4
Mode	12.0	8.0	8.6	9.5
Percentiles
99%	28.8	30.1	35.6	35.5
95%	22.6	23.7	25.8	26.6
90%	19.6	20.8	21.3	22.4
10%	5.6	6.3	5.8	6.7
5%	4.5	5.3	4.7	5.6
1%	3.0	3.4	2.9	3.6
Extremes
5 Highest Values
(Highest)	52.7	85.7	98.0	103.4
	51.4	77.9	87.1	79.1
	50.5	73.0	82.6	78.1
	48.9	64.3	75.8	76.7
	43.6	62.6	71.3	74.9
5 Lowest Values
	0.1	0.0	0.1	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
(Lowest)	0.0	0.0	0.0	0.0

Table 6.6
2002 NSDUH Audit Trail Timing Data: Total Tobacco Sections

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,560	22,811	15,193	42,754
Summary Statistics (Minutes)
Mean ()	2.0	2.1	2.3	2.5
Variance (2)	1.8	2.1	3.1	3.0
Standard Deviation ()	1.3	1.5	1.8	1.7
Quartiles
Maximum	13.8	35.1	35.5	41.5
Q3	2.5	2.6	3.1	3.2
Median	1.7	1.8	2.0	2.2
Q1	1.1	1.2	1.2	1.3
Minimum	0.0	0.0	0.0	0.0
Range	13.8	35.1	35.5	41.5
Mode	0.9	1.0	0.6	1.8
Percentiles
99%	6.9	7.2	8.4	8.3
95%	4.6	4.8	5.5	5.5
90%	3.7	3.9	4.4	4.5
10%	0.8	0.8	0.6	0.7
5%	0.7	0.7	0.4	0.5
1%	0.5	0.5	0.3	0.3
Extremes
5 Highest Values
(Highest)	13.8	35.1	35.5	41.5
	12.7	29.3	22.6	26.9
	12.0	25.9	22.1	26.6
	11.9	23.2	20.8	25.8
	11.3	21.5	20.5	25.7
5 Lowest Values
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
(Lowest)	0.0	0.0	0.0	0.0

Table 6.7
2002 NSDUH Audit Trail Timing Data: Alcohol Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,560	22,811	15,193	42,755
Summary Statistics (Minutes)
Mean ()	1.8	2.0	2.5	2.7
Variance (2)	1.8	1.9	3.2	2.7
Standard Deviation ()	1.3	1.4	1.8	1.6
Quartiles
Maximum	19.7	17.7	79.5	51.6
Q3	2.4	2.5	3.2	3.4
Median	1.5	1.8	2.2	2.4
Q1	0.8	0.9	1.4	1.6
Minimum	0.0	0.0	0.0	0.0
Range	19.7	17.7	79.5	51.6
Mode	0.6	2.3	2.4	2.3
Percentiles
99%	6.2	6.5	8.1	7.9
95%	4.3	4.6	5.4	5.5
90%	3.4	3.7	4.3	4.6
10%	0.4	0.5	0.8	1.0
5%	0.3	0.4	0.5	0.7
1%	0.2	0.2	0.2	0.3
Extremes
5 Highest Values
(Highest)	19.7	17.7	79.5	51.6
	14.2	16.5	47.6	49.3
	14.1	16.3	25.3	34.9
	13.9	14.0	21.6	30.3
	13.5	13.8	19.2	28.0
5 Lowest Values
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
(Lowest)	0.0	0.0	0.0	0.0

Table 6.8
2002 NSDUH Audit Trail Timing Data: Marijuana Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,558	22,810	15,189	42,747
Summary Statistics (Minutes)
Mean ()	0.5	0.5	0.5	0.6
Variance (2)	0.3	0.3	0.3	0.3
Standard Deviation ()	0.6	0.6	0.5	0.6
Quartiles
Maximum	10.1	11.0	17.7	29.2
Q3	0.6	0.6	0.7	0.7
Median	0.3	0.4	0.4	0.4
Q1	0.1	0.2	0.2	0.2
Minimum	0.0	0.0	0.0	0.0
Range	10.1	11.0	17.7	29.2
Mode	0.1	0.1	0.1	0.1
Percentiles
99%	2.6	2.7	2.4	2.5
95%	1.5	1.7	1.4	1.5
90%	1.1	1.2	1.0	1.2
10%	0.1	0.1	0.1	0.1
5%	0.1	0.1	0.1	0.1
1%	0.1	0.1	0.1	0.1
Extremes
5 Highest Values
(Highest)	10.1	11.0	17.7	29.2
	8.9	8.8	14.1	15.7
	7.5	8.5	8.9	14.6
	6.1	7.3	8.2	12.7
	5.4	7.2	8.1	9.6
5 Lowest Values
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
(Lowest)	0.0	0.0	0.0	0.0

Table 6.9
2002 NSDUH Audit Trail Timing Data: Cocaine & Crack Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,559	22,810	15,193	42,749
Summary Statistics (Minutes)
Mean ()	0.2	0.2	0.3	0.3
Variance (2)	0.1	0.1	0.2	0.2
Standard Deviation ()	0.3	0.3	0.4	0.4
Quartiles
Maximum	5.3	10.0	15.1	18.6
Q3	0.2	0.3	0.3	0.3
Median	0.1	0.2	0.1	0.2
Q1	0.1	0.1	0.1	0.1
Minimum	0.0	0.0	0.0	0.0
Range	5.3	10.0	15.1	18.6
Mode	0.1	0.1	0.1	0.1
Percentiles
99%	1.4	1.6	2.0	2.1
95%	0.4	0.4	0.9	1.0
90%	0.3	0.3	0.5	0.6
10%	0.1	0.1	0.1	0.1
5%	0.1	0.1	0.1	0.1
1%	0.0	0.0	0.0	0.0
Extremes
5 Highest Values
(Highest)	5.3	10.0	15.1	18.6
	5.2	6.9	11.8	14.2
	4.6	6.3	10.0	13.0
	4.2	6.0	9.3	10.7
	4.0	5.8	7.4	10.5
5 Lowest Values
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
(Lowest)	0.0	0.0	0.0	0.0

Table 6.10
2002 NSDUH Audit Trail Timing Data: Heroin Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,557	22,811	15,188	42,748
Summary Statistics (Minutes)
Mean ()	0.1	0.1	0.1	0.1
Variance (2)	0.0	0.1	0.2	0.0
Standard Deviation ()	0.1	0.3	0.5	0.1
Quartiles
Maximum	2.1	44.1	56.2	5.4
Q3	0.1	0.1	0.1	0.1
Median	0.1	0.1	0.1	0.1
Q1	0.1	0.1	0.1	0.1
Minimum	0.0	0.0	0.0	0.0
Range	2.1	44.1	56.2	5.4
Mode	0.1	0.1	0.1	0.1
Percentiles
99%	0.4	0.4	0.5	0.5
95%	0.2	0.2	0.3	0.3
90%	0.2	0.2	0.2	0.2
10%	0.1	0.1	0.0	0.0
5%	0.0	0.0	0.0	0.0
1%	0.0	0.0	0.0	0.0
Extremes
5 Highest Values
(Highest)	2.1	44.1	56.2	5.4
	2.0	13.3	12.8	4.2
	1.7	9.6	11.6	3.9
	1.7	7.9	9.6	3.9
	1.5	6.5	6.9	3.1
5 Lowest Values
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
(Lowest)	0.0	0.0	0.0	0.0

Table 6.11
2002 NSDUH Audit Trail Timing Data: Hallucinogen Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,559	22,813	15,194	42,755
Summary Statistics (Minutes)
Mean ()	0.9	1.0	0.9	0.9
Variance (2)	0.5	0.6	0.7	0.9
Standard Deviation ()	0.7	0.8	0.8	0.9
Quartiles
Maximum	12.1	25.3	28.1	59.2
Q3	1.2	1.3	1.1	1.2
Median	0.8	0.8	0.6	0.7
Q1	0.5	0.5	0.4	0.4
Minimum	0.0	0.0	0.0	0.0
Range	12.1	25.3	28.1	59.2
Mode	0.4	0.5	0.4	0.4
Percentiles
99%	3.4	3.6	3.7	3.7
95%	2.1	2.2	2.3	2.4
90%	1.8	1.8	1.8	1.9
10%	0.3	0.3	0.3	0.3
5%	0.2	0.3	0.2	0.2
1%	0.2	0.2	0.1	0.2
Extremes
5 Highest Values
(Highest)	12.1	25.3	28.1	59.2
	9.4	17.5	15.8	44.7
	8.5	16.9	12.0	37.7
	7.7	13.1	11.9	36.3
	7.5	12.5	10.7	35.2
5 Lowest Values
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
(Lowest)	0.0	0.0	0.0	0.0

Table 6.12
2002 NSDUH Audit Trail Timing Data: Inhalant Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,559	22,815	15,198	42,756
Summary Statistics (Minutes)
Mean ()	1.3	1.5	1.1	1.2
Variance (2)	0.9	1.4	1.1	0.9
Standard Deviation ()	1.0	1.2	1.0	1.0
Quartiles
Maximum	10.8	50.9	31.8	28.3
Q3	1.7	1.9	1.3	1.4
Median	1.1	1.2	0.8	0.9
Q1	0.7	0.8	0.6	0.6
Minimum	0.0	0.0	0.0	0.0
Range	10.8	50.9	31.8	28.3
Mode	0.5	0.8	0.5	0.6
Percentiles
99%	4.5	4.7	4.5	4.3
95%	3.1	3.3	3.1	3.1
90%	2.6	2.8	2.2	2.3
10%	0.4	0.5	0.4	0.4
5%	0.3	0.4	0.3	0.3
1%	0.2	0.2	0.2	0.2
Extremes
5 Highest Values
(Highest)	10.8	50.9	31.8	28.3
	10.7	48.7	19.6	24.2
	10.5	47.1	15.6	18.9
	9.0	34.2	15.6	18.6
	8.9	29.1	14.8	17.0
5 Lowest Values
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
(Lowest)	0.0	0.0	0.0	0.0

Table 6.13
2002 NSDUH Audit Trail Timing Data: Total Pill Sections

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,561	22,817	15,206	42,766
Summary Statistics (Minutes)
Mean ()	5.0	5.6	4.8	5.4
Variance (2)	8.3	8.4	10.9	10.2
Standard Deviation ()	2.9	2.9	3.3	3.2
Quartiles
Maximum	49.4	37.7	77.0	59.8
Q3	6.5	7.3	6.0	6.8
Median	4.4	5.2	4.1	4.7
Q1	2.9	3.5	2.7	3.3
Minimum	0.0	0.0	0.0	0.0
Range	49.4	37.7	77.0	59.8
Mode	4.2	4.2	2.9	4.1
Percentiles
99%	13.5	13.9	15.5	15.3
95%	10.5	10.9	11.1	11.6
90%	8.8	9.5	8.8	9.4
10%	1.9	2.4	1.8	2.3
5%	1.4	1.8	1.3	1.8
1%	0.8	1.0	0.7	1.0
Extremes
5 Highest Values
(Highest)	49.4	37.7	77.0	59.8
	27.5	35.5	59.5	52.1
	22.7	34.9	40.4	50.5
	22.5	33.6	40.1	49.0
	22.1	26.6	39.4	45.5
5 Lowest Values
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
(Lowest)	0.0	0.0	0.0	0.0

Table 6.14
2002 NSDUH Audit Trail Timing Data: Total Non-Core Sections

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,581	22,871	15,257	42,874
Summary Statistics (Minutes)
Mean ()	21.6	22.0	25.0	26.2
Variance (2)	64.3	59.2	141.5	125.4
Standard Deviation ()	8.0	7.7	11.9	11.2
Quartiles
Maximum	85.4	110.6	328.7	256.1
Q3	25.5	25.8	29.8	31.0
Median	20.3	20.9	22.5	24.0
Q1	16.2	16.9	17.3	18.8
Minimum	0.1	0.0	0.1	0.0
Range	85.3	110.6	328.6	256.1
Mode	15.0	19.9	20.6	21.7
Percentiles
99%	48.5	46.8	65.2	63.8
95%	35.7	35.8	46.8	46.8
90%	31.6	31.6	39.2	39.8
10%	13.1	13.8	13.6	15.1
5%	11.5	12.2	11.8	13.1
1%	8.5	9.1	7.8	9.7
Extremes
5 Highest Values
(Highest)	85.4	110.6	328.7	256.1
	79.5	107.2	169.9	241.5
	75.8	78.8	168.4	192.9
	73.8	76.0	167.5	155.0
	72.7	75.5	140.1	143.7
5 Lowest Values
	0.5	0.1	0.1	0.1
	0.4	0.1	0.1	0.1
	0.4	0.1	0.1	0.1
	0.2	0.1	0.1	0.1
(Lowest)	0.1	0.0	0.1	0.0

Table 6.15
2002 NSDUH Audit Trail Timing Data: Special Drugs Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,558	22,812	15,201	42,756
Summary Statistics (Minutes)
Mean ()	0.2	0.2	0.2	0.2
Variance (2)	0.1	0.1	0.1	0.2
Standard Deviation ()	0.3	0.4	0.4	0.4
Quartiles
Maximum	18.4	31.6	19.7	32.4
Q3	0.2	0.2	0.2	0.2
Median	0.2	0.2	0.2	0.2
Q1	0.1	0.1	0.1	0.1
Minimum	0.0	0.0	0.0	0.0
Range	18.4	31.6	19.7	32.4
Mode	0.1	0.2	0.1	0.1
Percentiles
99%	0.7	0.7	1.5	1.8
95%	0.4	0.4	0.5	0.5
90%	0.3	0.3	0.3	0.4
10%	0.1	0.1	0.1	0.1
5%	0.1	0.1	0.1	0.1
1%	0.0	0.0	0.0	0.0
Extremes
5 Highest Values
(Highest)	18.4	31.6	19.7	32.4
	5.2	18.9	15.8	22.3
	3.0	10.7	8.8	16.2
	3.0	10.7	7.7	11.2
	2.7	8.3	7.4	10.7
5 Lowest Values
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
(Lowest)	0.0	0.0	0.0	0.0

Table 6.16
2002 NSDUH Audit Trail Timing Data: Risk/Availability Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,558	22,821	15,208	42,773
Summary Statistics (Minutes)
Mean ()	4.9	5.1	4.9	5.0
Variance (2)	4.7	4.6	8.0	7.1
Standard Deviation ()	2.2	2.1	2.8	2.7
Quartiles
Maximum	29.2	63.7	79.5	68.2
Q3	5.9	6.0	5.6	5.8
Median	4.5	4.7	4.2	4.4
Q1	3.5	3.7	3.2	3.4
Minimum	0.0	0.0	0.0	0.0
Range	29.2	63.7	79.5	68.2
Mode	3.8	4.4	3.2	3.6
Percentiles
99%	12.6	12.3	15.4	14.8
95%	8.8	8.8	10.0	9.9
90%	7.4	7.5	7.9	7.8
10%	2.8	3.0	2.6	2.8
5%	2.4	2.6	2.3	2.5
1%	1.8	2.0	1.7	1.8
Extremes
5 Highest Values
(Highest)	29.2	63.7	79.5	68.2
	25.1	41.9	49.8	58.3
	24.1	39.6	46.8	57.1
	23.0	29.9	41.9	53.7
	20.9	28.5	37.0	49.4
5 Lowest Values
	0.1	0.0	0.0	0.0
	0.1	0.0	0.0	0.0
	0.1	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
(Lowest)	0.0	0.0	0.0	0.0

Table 6.17
2002 NSDUH Audit Trail Timing Data: Specialty Cigarettes

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,555	22,820	15,203	42,761
Summary Statistics (Minutes)
Mean ()	0.4	0.4	0.4	0.4
Variance (2)	0.1	0.1	0.1	0.1
Standard Deviation ()	0.3	0.3	0.4	0.4
Quartiles
Maximum	4.3	8.2	16.2	28.6
Q3	0.5	0.5	0.5	0.5
Median	0.4	0.4	0.3	0.4
Q1	0.2	0.3	0.2	0.3
Minimum	0.0	0.0	0.0	0.0
Range	4.3	8.2	16.2	28.6
Mode	0.2	0.3	0.3	0.3
Percentiles
99%	1.4	1.3	1.6	1.5
95%	0.8	0.8	0.9	0.9
90%	0.6	0.6	0.7	0.7
10%	0.2	0.2	0.2	0.2
5%	0.1	0.2	0.1	0.2
1%	0.1	0.1	0.1	0.1
Extremes
5 Highest Values
(Highest)	4.3	8.2	16.2	28.6
	3.9	6.0	15.2	18.3
	3.6	5.9	14.0	13.1
	3.2	4.8	9.0	9.7
	2.9	4.7	6.6	9.2
5 Lowest Values
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
(Lowest)	0.0	0.0	0.0	0.0

Table 6.18
2002 NSDUH Audit Trail Timing Data: Drug Dependence & Abuse Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	2,286	7,258	10,648	31,361
Summary Statistics (Minutes)
Mean ()	4.6	4.8	4.3	4.6
Variance (2)	9.8	9.8	10.3	10.3
Standard Deviation ()	3.1	3.1	3.2	3.2
Quartiles
Maximum	28.7	39.2	74.4	58.2
Q3	6.0	6.2	5.6	6.1
Median	3.7	3.8	3.5	3.8
Q1	2.4	2.6	2.1	2.3
Minimum	0.1	0.0	0.0	0.0
Range	28.7	39.2	74.4	58.2
Mode	2.1	2.7	1.7	2.2
Percentiles
99%	15.4	15.3	15.3	15.5
95%	10.7	10.9	10.0	10.6
90%	8.6	8.9	8.0	8.6
10%	1.7	1.9	1.5	1.6
5%	1.4	1.5	1.2	1.4
1%	0.7	0.9	0.8	0.9
Extremes
5 Highest Values
(Highest)	28.7	39.2	74.4	58.2
	25.1	30.2	44.9	56.1
	25.0	28.3	40.1	50.7
	24.9	26.6	39.9	47.2
	23.1	25.4	34.6	43.4
5 Lowest Values
	0.3	0.1	0.0	0.0
	0.2	0.1	0.0	0.0
	0.2	0.1	0.0	0.0
	0.1	0.0	0.0	0.0
(Lowest)	0.1	0.0	0.0	0.0

Table 6.19
2002 NSDUH Audit Trail Timing Data: Marketing Information for Marijuana Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	1,127	3,626	2,426	8,592
Summary Statistics (Minutes)
Mean ()	1.6	1.6	1.5	1.6
Variance (2)	0.6	0.5	0.9	0.6
Standard Deviation ()	0.8	0.7	1.0	0.8
Quartiles
Maximum	8.7	6.3	12.5	14.8
Q3	2.0	1.9	1.9	1.9
Median	1.5	1.5	1.4	1.5
Q1	1.1	1.1	1.0	1.0
Minimum	0.0	0.0	0.0	0.0
Range	8.7	6.3	12.5	14.8
Mode	1.1	1.1	0.8	1.0
Percentiles
99%	4.2	3.7	4.9	3.9
95%	2.9	2.7	2.9	2.8
90%	2.5	2.4	2.5	2.5
10%	0.8	0.9	0.7	0.8
5%	0.7	0.7	0.6	0.7
1%	0.3	0.4	0.3	0.5
Extremes
5 Highest Values
(Highest)	8.7	6.3	12.5	14.8
	5.5	6.2	12.4	11.6
	5.3	6.1	11.7	10.6
	5.3	6.0	10.9	10.6
	4.8	5.9	10.7	10.2
5 Lowest Values
	0.1	0.0	0.0	0.1
	0.1	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
(Lowest)	0.0	0.0	0.0	0.0

Table 6.20
2002 NSDUH Audit Trail Timing Data: Special Topics, Drug Treatment and Health Care Module

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,560	22,832	15,208	42,781
Summary Statistics (Minutes)
Mean ()	2.1	2.1	2.5	2.6
Variance (2)	1.5	1.6	4.0	2.7
Standard Deviation ()	1.2	1.3	2.0	1.7
Quartiles
Maximum	21.8	41.4	152.7	50.7
Q3	2.4	2.4	2.9	2.9
Median	1.8	1.8	2.1	2.2
Q1	1.4	1.4	1.6	1.7
Minimum	0.0	0.0	0.0	0.0
Range	21.8	41.4	152.7	50.7
Mode	1.5	1.5	1.9	1.7
Percentiles
99%	7.0	7.3	8.8	9.1
95%	4.0	4.0	5.1	5.3
90%	3.2	3.2	4.1	4.1
10%	1.1	1.2	1.2	1.3
5%	1.0	1.0	1.1	1.2
1%	0.7	0.8	0.8	0.9
Extremes
5 Highest Values
(Highest)	21.8	41.4	152.7	50.7
	15.1	38.8	37.9	41.5
	15.0	35.1	31.5	39.2
	14.8	25.1	30.8	35.9
	14.5	19.1	25.7	32.9
5 Lowest Values
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
	0.0	0.0	0.0	0.0
(Lowest)	0.0	0.0	0.0	0.0

Table 6.21
2002 NSDUH Audit Trail Timing Data: Adult Mental Health Service Utilization Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	N/A	N/A	15,206	42,782
Summary Statistics (Minutes)
Mean ()	N/A	N/A	0.8	0.9
Variance (2)	N/A	N/A	0.7	1.0
Standard Deviation ()	N/A	N/A	0.9	1.0
Quartiles
Maximum	N/A	N/A	27.2	43.4
Q3	N/A	N/A	1.0	1.0
Median	N/A	N/A	0.6	0.7
Q1	N/A	N/A	0.4	0.5
Minimum	N/A	N/A	0.0	0.0
Range	N/A	N/A	27.2	43.4
Mode	N/A	N/A	0.5	0.5
Percentiles
99%	N/A	N/A	4.1	4.6
95%	N/A	N/A	2.2	2.5
90%	N/A	N/A	1.6	1.9
10%	N/A	N/A	0.3	0.4
5%	N/A	N/A	0.2	0.3
1%	N/A	N/A	0.1	0.2
Extremes
5 Highest Values
(Highest)	N/A	N/A	27.2	43.4
	N/A	N/A	16.2	35.9
	N/A	N/A	14.5	30.3
	N/A	N/A	13.6	27.7
	N/A	N/A	12.9	26.3
5 Lowest Values
	N/A	N/A	0.0	0.0
	N/A	N/A	0.0	0.0
	N/A	N/A	0.0	0.0
	N/A	N/A	0.0	0.0
(Lowest)	N/A	N/A	0.0	0.0

Table 6.22
2002 NSDUH Audit Trail Timing Data: Social Environment Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	N/A	N/A	15,218	42,803
Summary Statistics (Minutes)
Mean ()	N/A	N/A	5.3	5.2
Variance (2)	N/A	N/A	8.7	6.0
Standard Deviation ()	N/A	N/A	2.9	2.4
Quartiles
Maximum	N/A	N/A	90.9	64.3
Q3	N/A	N/A	6.2	6.1
Median	N/A	N/A	4.7	4.7
Q1	N/A	N/A	3.6	3.6
Minimum	N/A	N/A	0.0	0.0
Range	N/A	N/A	90.9	64.3
Mode	N/A	N/A	4.4	3.8
Percentiles
99%	N/A	N/A	15.2	14.0
95%	N/A	N/A	10.0	9.6
90%	N/A	N/A	8.3	8.0
10%	N/A	N/A	2.8	2.9
5%	N/A	N/A	2.4	2.5
1%	N/A	N/A	1.6	1.9
Extremes
5 Highest Values
(Highest)	N/A	N/A	90.9	64.3
	N/A	N/A	76.6	46.7
	N/A	N/A	66.7	43.6
	N/A	N/A	49.8	39.4
	N/A	N/A	47.3	39.3
5 Lowest Values
	N/A	N/A	0.0	0.0
	N/A	N/A	0.0	0.0
	N/A	N/A	0.0	0.0
	N/A	N/A	0.0	0.0
(Lowest)	N/A	N/A	0.0	0.0

Table 6.23
2002 NSDUH Audit Trail Timing Data: Parenting Experiences Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	N/A	N/A	1,273	3,810
Summary Statistics (Minutes)
Mean ()	N/A	N/A	3.1	3.1
Variance (2)	N/A	N/A	4.3	2.4
Standard Deviation ()	N/A	N/A	2.1	1.6
Quartiles
Maximum	N/A	N/A	44.5	26.0
Q3	N/A	N/A	3.6	3.7
Median	N/A	N/A	2.7	2.7
Q1	N/A	N/A	2.0	2.1
Minimum	N/A	N/A	0.0	0.1
Range	N/A	N/A	44.5	26.0
Mode	N/A	N/A	1.9	2.3
Percentiles
99%	N/A	N/A	10.3	8.7
95%	N/A	N/A	6.3	6.0
90%	N/A	N/A	5.0	5.0
10%	N/A	N/A	1.6	1.7
5%	N/A	N/A	1.4	1.5
1%	N/A	N/A	0.9	1.2
Extremes
5 Highest Values
(Highest)	N/A	N/A	44.5	26.0
	N/A	N/A	15.7	18.0
	N/A	N/A	15.6	14.6
	N/A	N/A	14.6	14.0
	N/A	N/A	13.3	13.6
5 Lowest Values
	N/A	N/A	0.4	0.3
	N/A	N/A	0.2	0.2
	N/A	N/A	0.2	0.1
	N/A	N/A	0.1	0.1
(Lowest)	N/A	N/A	0.0	0.1

Table 6.24
2002 NSDUH Audit Trail Timing Data: Serious Mental Illness Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	N/A	N/A	15,239	42,853
Summary Statistics (Minutes)
Mean ()	N/A	N/A	6.8	7.2
Variance (2)	N/A	N/A	22.9	20.1
Standard Deviation ()	N/A	N/A	4.8	4.5
Quartiles
Maximum	N/A	N/A	210.9	213.8
Q3	N/A	N/A	8.5	8.9
Median	N/A	N/A	5.7	6.2
Q1	N/A	N/A	3.9	4.3
Minimum	N/A	N/A	0.0	0.0
Range	N/A	N/A	210.9	213.8
Mode	N/A	N/A	4.1	4.8
Percentiles
99%	N/A	N/A	23.1	22.3
95%	N/A	N/A	15.1	15.1
90%	N/A	N/A	12.1	12.3
10%	N/A	N/A	2.7	3.1
5%	N/A	N/A	2.1	2.5
1%	N/A	N/A	0.9	1.4
Extremes
5 Highest Values
(Highest)	N/A	N/A	210.9	213.8
	N/A	N/A	71.3	194.3
	N/A	N/A	55.7	81.9
	N/A	N/A	55.5	73.5
	N/A	N/A	55.1	73.0
5 Lowest Values
	N/A	N/A	0.0	0.0
	N/A	N/A	0.0	0.0
	N/A	N/A	0.0	0.0
	N/A	N/A	0.0	0.0
(Lowest)	N/A	N/A	0.0	0.0

Table 6.25
2002 NSDUH Audit Trail Timing Data: Youth Experiences Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,571	22,853	N/A	N/A
Summary Statistics (Minutes)
Mean ()	10.1	10.1	N/A	N/A
Variance (2)	14.3	12.0	N/A	N/A
Standard Deviation ()	3.8	3.5	N/A	N/A
Quartiles
Maximum	45.5	46.4	N/A	N/A
Q3	11.9	11.8	N/A	N/A
Median	9.6	9.7	N/A	N/A
Q1	7.6	7.8	N/A	N/A
Minimum	0.1	0.0	N/A	N/A
Range	45.5	46.4	N/A	N/A
Mode	7.7	10.3	N/A	N/A
Percentiles
99%	22.9	21.3	N/A	N/A
95%	16.6	16.0	N/A	N/A
90%	14.5	14.2	N/A	N/A
10%	6.1	6.4	N/A	N/A
5%	5.3	5.6	N/A	N/A
1%	3.4	3.8	N/A	N/A
Extremes
5 Highest Values
(Highest)	45.5	46.4	N/A	N/A
	41.2	44.5	N/A	N/A
	40.3	41.4	N/A	N/A
	39.3	40.2	N/A	N/A
	39.0	37.7	N/A	N/A
5 Lowest Values
	0.4	0.1	N/A	N/A
	0.3	0.0	N/A	N/A
	0.3	0.0	N/A	N/A
	0.2	0.0	N/A	N/A
(Lowest)	0.1	0.0	N/A	N/A

Table 6.26
2002 NSDUH Audit Trail Timing Data: Youth Mental Health Service Utilization Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,574	22,865	N/A	N/A
Summary Statistics (Minutes)
Mean ()	1.6	1.7	N/A	N/A
Variance (2)	2.0	1.8	N/A	N/A
Standard Deviation ()	1.4	1.3	N/A	N/A
Quartiles
Maximum	29.9	37.6	N/A	N/A
Q3	2.0	2.1	N/A	N/A
Median	1.3	1.4	N/A	N/A
Q1	0.8	0.9	N/A	N/A
Minimum	0.0	0.0	N/A	N/A
Range	29.9	37.6	N/A	N/A
Mode	1.0	1.0	N/A	N/A
Percentiles
99%	6.8	6.6	N/A	N/A
95%	4.1	4.0	N/A	N/A
90%	3.1	3.1	N/A	N/A
10%	0.5	0.6	N/A	N/A
5%	0.4	0.4	N/A	N/A
1%	0.2	0.2	N/A	N/A
Extremes
5 Highest Values
(Highest)	29.9	37.6	N/A	N/A
	25.7	26.9	N/A	N/A
	22.4	25.9	N/A	N/A
	20.0	25.0	N/A	N/A
	16.3	20.4	N/A	N/A
5 Lowest Values
	0.0	0.0	N/A	N/A
	0.0	0.0	N/A	N/A
	0.0	0.0	N/A	N/A
	0.0	0.0	N/A	N/A
(Lowest)	0.0	0.0	N/A	N/A

Table 6.27
2002 NSDUH Audit Trail Timing Data: Total Back-End FI Administered

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,593	22,910	15,266	42,933
Summary Statistics (Minutes)
Mean ()	10.2	11.0	11.0	11.9
Variance (2)	29.2	275.4	70.4	26.7
Standard Deviation ()	5.4	16.6	8.4	5.2
Quartiles
Maximum	105.2	2,370.7	830.5	86.7
Q3	12.5	13.3	13.1	14.1
Median	9.2	10.0	10.1	11.0
Q1	6.6	7.3	7.7	8.5
Minimum	0.2	0.1	0.2	0.1
Range	105.1	2,370.6	830.3	86.6
Mode	8.2	6.6	8.9	10.3
Percentiles
99%	28.1	28.6	28.1	29.5
95%	19.4	20.0	19.9	20.9
90%	16.4	17.0	16.9	17.8
10%	4.9	5.5	5.9	6.7
5%	4.1	4.7	4.9	5.7
1%	2.8	3.3	3.2	3.9
Extremes
5 Highest Values
(Highest)	105.2	2,370.7	830.5	86.7
	76.3	218.7	134.9	81.3
	60.3	179.9	99.0	75.0
	57.0	164.3	57.1	74.8
	56.7	97.4	57.1	73.7
5 Lowest Values
	0.7	0.3	0.3	0.3
	0.4	0.2	0.3	0.2
	0.3	0.2	0.3	0.2
	0.2	0.1	0.2	0.1
(Lowest)	0.2	0.1	0.2	0.1

Table 6.28
2002 NSDUH Audit Trail Timing Data: Back-End Demographics Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,579	22,882	15,252	42,894
Summary Statistics (Minutes)
Mean ()	4.4	4.7	6.4	6.8
Variance (2)	10.1	252.5	12.9	11.4
Standard Deviation ()	3.2	15.9	3.6	3.4
Quartiles
Maximum	73.8	2,364.9	133.7	72.9
Q3	5.7	6.0	7.8	8.2
Median	3.5	3.8	5.9	6.3
Q1	2.3	2.5	4.3	4.8
Minimum	0.4	0.0	0.0	0.0
Range	73.4	2,364.9	133.7	72.9
Mode	2.4	2.7	5.2	5.5
Percentiles
99%	14.1	14.0	18.0	18.1
95%	9.9	10.1	12.1	12.5
90%	8.3	8.4	10.2	10.5
10%	1.7	1.8	2.8	3.3
5%	1.4	1.5	2.1	2.4
1%	1.0	1.1	1.2	1.4
Extremes
5 Highest Values
(Highest)	73.8	2,364.9	133.7	72.9
	44.3	89.6	66.2	63.5
	43.7	63.5	54.8	61.9
	43.5	45.4	48.0	60.9
	42.0	45.1	44.5	57.4
5 Lowest Values
	0.5	0.2	0.2	0.2
	0.5	0.1	0.2	0.1
	0.5	0.1	0.1	0.1
	0.4	0.1	0.1	0.0
(Lowest)	0.4	0.0	0.0	0.0

Table 6.29
2002 NSDUH Audit Trail Timing Data: Income Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,591	22,909	15,264	42,933
Summary Statistics (Minutes)
Mean ()	3.7	4.1	3.3	3.7
Variance (2)	6.3	8.8	48.5	6.4
Standard Deviation ()	2.5	3.0	7.0	2.5
Quartiles
Maximum	52.7	175.8	818.1	67.8
Q3	4.5	5.0	3.9	4.4
Median	3.2	3.6	2.8	3.1
Q1	2.1	2.5	1.9	2.3
Minimum	0.2	0.1	0.1	0.0
Range	52.5	175.7	818.0	67.7
Mode	2.5	3.1	1.9	2.6
Percentiles
99%	13.0	13.3	11.3	12.7
95%	7.6	8.0	6.8	7.3
90%	6.2	6.6	5.4	5.9
10%	1.4	1.8	1.4	1.7
5%	1.2	1.4	1.1	1.4
1%	0.7	0.9	0.7	0.9
Extremes
5 Highest Values
(Highest)	52.7	175.8	818.1	67.8
	45.1	88.9	50.2	58.7
	39.1	59.9	42.3	57.3
	30.4	58.4	42.1	57.3
	26.2	54.4	39.1	50.0
5 Lowest Values
	0.3	0.2	0.1	0.2
	0.2	0.2	0.1	0.1
	0.2	0.1	0.1	0.1
	0.2	0.1	0.1	0.1
(Lowest)	0.2	0.1	0.1	0.0

Table 6.30
2002 NSDUH Audit Trail Timing Data: FI Observation Section

Age Category	12–17		18 +
Year of Interest	2001	2002	2001	2002
Sample Size	7,598	22,935	15,278	42,983
Summary Statistics (Minutes)
Mean ()	1.5	2.4	1.7	2.4
Variance (2)	11.5	14.2	34.6	14.4
Standard Deviation ()	3.4	3.8	5.9	3.8
Quartiles
Maximum	207.3	326.5	530.7	314.0
Q3	1.7	2.7	1.7	2.7
Median	0.9	1.7	1.0	1.7
Q1	0.5	1.1	0.5	1.1
Minimum	0.1	0.0	0.0	0.0
Range	207.2	326.4	530.6	314.0
Mode	0.3	0.8	0.4	1.0
Percentiles
99%	10.4	11.4	11.5	12.5
95%	4.1	5.8	4.5	5.9
90%	2.9	4.4	3.0	4.3
10%	0.3	0.8	0.3	0.8
5%	0.3	0.6	0.3	0.6
1%	0.2	0.5	0.2	0.5
Extremes
5 Highest Values
(Highest)	207.3	326.5	530.7	314.0
	63.4	140.2	226.4	245.4
	61.5	132.7	145.1	224.0
	51.8	117.0	138.6	178.1
	48.8	112.9	122.4	154.4
5 Lowest Values
	0.1	0.1	0.1	0.0
	0.1	0.1	0.1	0.0
	0.1	0.1	0.1	0.0
	0.1	0.1	0.0	0.0
(Lowest)	0.1	0.0	0.0	0.0

Table 6.31
2002 NSDUH Audit Trail Timing Data: Back-End Demographics Among 15 + By Employment Status

Employment Status	Employed		Not Employed
Year of Interest	2001	2002	2001	2002
Sample Size	12,776	35,734	6,261	18,254
Summary Statistics (Minutes)
Mean ()	7.2	7.6	4.5	4.8
Variance (2)	11.9	10.3	8.6	7.8
Standard Deviation ()	3.4	3.2	2.9	2.8
Quartiles
Maximum	133.7	72.9	44.3	63.5
Q3	8.4	8.8	5.5	6.0
Median	6.5	7.0	3.8	4.3
Q1	5.2	5.6	2.6	2.9
Minimum	0.0	0.0	0.2	0.0
Range	133.7	72.9	44.2	63.5
Mode	6.3	6.3	2.3	3.3
Percentiles
99%	18.7	18.9	13.9	14.0
95%	12.7	13.1	9.6	9.7
90%	10.8	11.1	7.9	8.1
10%	4.2	4.6	1.8	2.1
5%	3.6	4.0	1.5	1.7
1%	2.6	3.1	0.9	1.1
Extremes
5 Highest Values
(Highest)	133.7	72.9	44.3	63.5
	66.2	63.5	42.0	50.7
	54.8	61.9	36.2	44.4
	48.0	60.9	35.8	40.6
	44.5	57.4	32.3	36.7
5 Lowest Values
	0.2	0.2	0.3	0.3
	0.2	0.2	0.3	0.3
	0.1	0.1	0.2	0.2
	0.1	0.1	0.2	0.2
(Lowest)	0.0	0.0	0.2	0.0

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