TITLE: Crack, Powder Cocaine, and Heroin: Drug Purchase and Use Patterns in Six U.S. Cities.
Series: NIJ Research Report
Published: December 1997
Subject: ADAM, drug abuse, drug policies, drug testing
25 pages
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National Institute of Justice &
Office of National Drug Control Policy
Crack, Powder Cocaine, and Heroin: Drug Purchase and Use Patterns in
Six U.S. Cities
Executive Office of the President
Office of National Drug Control Policy
Washington, DC 20503
Barry R. McCaffrey
Director
U. S. Department of Justice
Office of Justice Programs
810 Seventh Street N.W.
Washington, DC 20531
Janet Reno
Attorney General
U.S. Department of Justice
Raymond C. Fisher
Associate Attorney General
Laurie Robinson
Assistant Attorney General
Noel Brennan
Deputy Assistant Attorney General
Jeremy Travis
Director, National Institute of Justice
Office of Justice Programs World Wide Web Site:
http://www.ojp.usdoj.gov
National Institute of Justice World Wide Web Site:
http://www.ojp.usdoj.gov/nij
Office of National Drug Control Policy World Wide Web Site:
http://www.whitehousedrugpolicy.gov
Crack, Powder Cocaine, and Heroin: Drug Purchase and Use Patterns in
Six U.S. Cities
K. Jack Riley
December 1997
A report on research conducted under the joint auspices of the National
Institute of Justice and the Office of National Drug Control Policy
Office of National Drug Control Policy
Barry R. McCaffrey
Director
National Institute of Justice
Jeremy Travis
Director
K. Jack Riley, Ph.D., is director of the Arrestee Drug Abuse Monitoring
program at the National Institute of Justice.
-------------------------------------------------------
Opinions or points of view expressed in this document do not necessarily
reflect the official position of the U.S. Department of Justice or the Office
of National Drug Control Policy.
The National Institute of Justice is a component of the Office of Justice
Programs, which also includes the Bureau of Justice Assistance, the
Bureau of Justice Statistics, the Office of Juvenile Justice and Delinquency
Prevention, and the Office for the Victims of Crime.
-------------------------------------------------------
NCJ 167265
Contents
Acknowledgments     
Executive Summary   
Summary of User Findings
Summary of Purchase Patterns
Summary of Use Patterns
Study Methodology   
Profile of Users 
Age
Living Arrangements
Sources of Income
Arrest Charges
Race and Drug Use
Purchase Patterns 
Buyer-Seller Relations
Dealer Networks
Location of Purchases
Failed Transactions
Purchase Frequency
Guns and Drug Purchases
Use Patterns 
Three-Day Use
Daily Use
Duration of Use
Cessation of Use
Conclusions and Implications 
Drug User Profile
Drug Purchase Patterns
Drug Use Patterns
Policy Implications
Notes 
Appendix 
-------------------------------------------------------
Acknowledgments
The National Institute of Justice (NIJ) and the Office of National Drug
Control Policy (ONDCP) would like to acknowledge the contributions of
individuals and organizations whose efforts made this project possible.
ONDCP provided the resources to fund the project. NIJ provided staff
resources and access to the Drug Use Forecasting (DUF) sites that
participated in the project. Staff of BOTEC Analysis Corporation --
including Ann Marie Rocheleau, Jennifer Jackson, and Andrew Lockwood
Chalsma -- were key to designing the interview instrument, conducting
training, and preparing the data. Similarly, Rosalee Copeland and Jeremy
Yuan at Aspen Systems Corporation's Applied Management Sciences
Group provided data runs and cross-checks between addendum data and
DUF data. NIJ and ONDCP staff provided thoughtful suggestions for the
project and helpful reviews of draft reports. In addition, two anonymous
reviewers provided valuable critiques of an early draft. Many DUF site
staff contributed to making this project happen by collecting the data, and
their cooperation is greatly appreciated: James Swartz, Scott Slomka, and
Norm Hamilton (Chicago); Bruce D. Johnson, Tom Miller, Phyllis Curry,
Elliott Quinones, and Diane Concepcion (Manhattan); Diane Wiscarson
(Portland, Oregon); Ed Baca and James Daniels (San Antonio); Susan
Pennell and Ami Caldwell (San Diego); and LaVon Williams
(Washington, D.C.). Special thanks go out to Bruce D. Johnson, Susan
Pennell, and Ami Caldwell for their work on developing the interview
instrument and the training curriculum.
-------------------------------------------------------
Crack, Powder Cocaine, and Heroin: Drug Purchase and Use Patterns in
Six U.S. Cities
Executive Summary
This document presents information collected from 2,056 recently arrested
powder cocaine, crack cocaine, and heroin users from Chicago;
Manhattan; Portland, Oregon; San Antonio; San Diego; and Washington,
D.C. It highlights information concerning where and how arrestees
obtained and used drugs. Researchers used a survey with approximately
100 questions to gather information on the proximity of drug purchases to
the buyer's home and neighborhood; the buyer's relationship to the seller;
the elapsed time, duration, and frequency of purchases; the size and price
of drug transactions; how income is generated for drug purchases; the
presence of firearms during drug transactions; quantities of drugs typically
used; the form of drug and mode of administration; frequency of drug use
and cessation; reasons for cessation; and polydrug use patterns.
The analysis revealed significant differences within and across drug types.
Furthermore, within a given drug type (such as crack) significant
differences existed across cities, across racial, ethnic, or age groups, or
across other such definable subgroups. Across drug types, there were
nearly always differences, no matter what demographic or summary
measure was considered. Unless otherwise specified, the results include
adult males and females but exclude juveniles. 
Summary of User Findings
o Crack users reported living in shelters or on the streets more frequently
than did other drug users in most sites. About 11.5 percent of crack users
in Washington, D.C., and 8.5 percent in Manhattan reported living in a
shelter prior to arrest; 16 percent of crack users in San Diego, 13 percent
in Manhattan, and 12 percent in San Antonio reported being on the streets
prior to arrest.
o Substantial fractions of respondents across all drug types reported that
public assistance was their primary source of income prior to arrest. In
some cities, certain drug users (such as Manhattan crack users) were more
likely to report public assistance as their main form of income than full-
and part-time work combined.
o White and Hispanic participants spread their drug use relatively evenly
across the powder, crack, heroin, and combination heroin markets. Black
participants primarily used crack.
Summary of Purchase Patterns
o Heroin and powder cocaine users were more likely to report using a
main source (a single individual) than crack users.
o For most drugs in most sites, white drug users were more likely than
black drug users to report using a main source.
o Respondents were most likely to report using a main source who was of
their own racial or ethnic background, regardless of the drug considered.
o On average, crack users reported knowing more dealers from whom they
could make purchases than did powder and heroin users. 
o A large majority of crack and heroin users reported that they typically
made purchases outdoors. Smaller (though still large) fractions of powder
purchasers reported that they usually bought drugs outdoors.
o Similarly, crack and heroin users were more likely than powder users to
report that they usually made their purchases in their own neighborhoods.
o Users reported that substantial majorities of indoor purchases were made
in residences. Powder users reported that they typically made indoor
purchases in places of business more frequently than did other users.
o Large fractions of respondents (although not a majority in most cities or
for most drugs) reported being unable to complete a drug purchase at least
once in the year prior to arrest. The inability to locate a dealer and the
dealer's lack of supply were frequently offered as explanations for failed
purchase attempts. In addition, large fractions of Manhattan respondents
reported police activity as the reason for their failed transactions.
o Substantial majorities of respondents from all drug use categories and all
sites reported making at least one purchase in the week before arrest.
Among these, powder users recorded the lowest mean number of
purchases (ranging from 3 to 9); heroin and crack users reported much
higher mean numbers of purchases in the week prior to arrest (ranging
from 6 to 15 for heroin and 6 to 14 for crack).
Summary of Use Patterns
o Study participants were very likely to test positive for drugs, indicating
that they had used narcotics in the 72 hours before arrest. In all sites, 90
percent or more of the crack respondents tested positive for cocaine, and
more than 75 percent of the heroin respondents tested positive for opiates.
In five out of six sites, more than 70 percent of the powder respondents
tested positive for cocaine.
o In most sites, substantial majorities of heroin users described themselves
as daily users. In contrast, approximately 40 to 50 percent of crack users
and 10 to 40 percent of powder users described themselves as daily users.
o Among those describing themselves as daily users, powder and crack
users generally reported consuming their drug more times per day than did
heroin users.
o Larger proportions of heroin users than of powder or crack users
reported daily or near- daily use in the 90 days prior to arrest.
o A majority of powder users in Manhattan claimed that periods of nonuse
or abstinence in the 90 days prior to arrest formed part of their regular use
patterns, and similar trends were found in other sites. A plurality of crack
and heroin users also reported that their regular patterns included periods
of nonuse. Substantial fractions of Manhattan crack users reported cost
("could not afford") and being "tired of [the drug] life" as an explanation
for periods of nonuse. Among heroin users in Manhattan, more than
one-third attributed a recent period of abstinence to either being in
treatment programs (nearly 24 percent) or being incarcerated (nearly 12
percent).
In summary, these findings suggest that the powder, crack, and heroin
markets differ substantially from one another in a variety of ways,
including how users buy and consume the drugs. Detailed information
about drug habits and patterns would be a valuable tool for local law
enforcement officials, service providers, and policymakers.
In terms of specific drugs and markets, crack stands out for its significant
exposure to law enforcement intervention. Crack transactions are more
frequent than powder or heroin transactions (in aggregate), and crack
transactions are more likely to take place under conditions that expose
users to risk of arrest (for example, outdoors, where they are visible to law
enforcement). In addition, crack users also have more extensive networks
of dealers; these wider networks introduce additional risks, including the
opportunity for compromise by law enforcement. 
When reviewing the results of this study, it is important to remember that
two design factors prevent the patterns and characteristics exhibited by
study participants from being representative of drug users in any other
locations. First, these six cities are distinguished by their high rates of
heroin use. Second, the population interviewed as part of this project
consisted entirely of individuals who were arrested; it is likely that drug
users who have not been arrested engage in different drug use and
procurement patterns. 
Even so, the results suggest that the arrestee population is appropriate for
exploring motivations for drug use and the impact of policy interventions.
With appropriate questions, arrestee interviews could explore such critical
factors as deterrence, substitution of one drug for another, and the
interaction between policing operations and the need for treatment
services.
Study Methodology
In 1993 and 1994, the Office of National Drug Control Policy (ONDCP)
demonstrated that heroin users could be interviewed to describe various
aspects of drug market activity, including the length of time it takes heroin
users to locate and purchase the drug.[1] Improving the understanding of
search costs more accurately portrayed the full costs users pay for drugs
and helped policymakers identify factors that affect the availability of
drugs. In 1995 ONDCP, in collaboration with the National Institute of
Justice (NIJ), extended this analysis to include two additional drugs --
powder cocaine and crack cocaine. This new study, called the procurement
study, was executed as an addendum to NIJ's Drug Use Forecasting
(DUF) program[2] and sought to explore additional features of drug
market participation and use, both within and across drug types and cities.
While earlier market studies involved developing separate data collection
samples, the procurement study was fielded as a supplement to the
ongoing interviews of arres-tees as part of the DUF program. The study
was exploratory and was intended to address the practical and policy
implications of different drug market participation patterns. Although this
study cannot identify what policies work best in a given drug market, it
does provide important insights on how drug markets differ and how drug
users and drug markets are affected by different circumstances.
The procurement study, which added 100 questions to the DUF interview,
was implemented quarterly for 1 year in six DUF sites (Chicago;
Manhattan; Portland, Oregon; San Antonio; San Diego; and Washington,
D.C.). These sites were selected because they had consistently shown the
highest rates of heroin use among the DUF sites, and they had substantial
levels of cocaine use. It was important to select cities with a high heroin
prevalence in order to ensure that the study included an adequate number
of heroin users.[3]
The DUF interview consists of fewer than 30 questions and is currently
implemented in 23 sites nationwide. The questions generate major
demographic and descriptive data, including age, gender, race or ethnicity,
education, living arrangements, sources and amounts of income, marital
status, drug treatment history, self-assessment of need for treatment,
emergency room history, and recent criminal behavior. At the end of the
interview, respondents -- all of whom are recent arrestees -- are asked to
provide a urine specimen that is tested for 10 drugs, in order to validate
their self-reported drug use.[4] Since the drug-screening assay cannot
reliably detect most drugs beyond 72 hours after use, arrestees who have
been incarcerated for more than 48 hours do not qualify for the DUF
interview. During the procurement study period (third quarter of 1995
through second quarter of 1996), more than 11,000 arrestees in the six
procurement study sites were asked to participate in the DUF interview. Of
these, 8,981 agreed to participate in the main DUF interview and to
provide a urine specimen. Table 1 provides a summary of participation in
the DUF by study city.
Eligibility for the procurement study was defined as having completed the
main DUF questionnaire and having reported powder, crack, or heroin use
in the 30 days prior to arrest.[5] Arrestees who reported having used more
than one type of drug during the 30 days preceding arrest were eligible for
more than one interview.[6] More than 2,900 individuals were eligible to
participate in the procurement study, potentially representing 3,603
completed interviews (see table 2). 
A total of 2,056 drug users were interviewed for the procurement study.
Study interviews were conducted with about 42 percent of the eligible
powder users, 70 percent of the eligible crack users, and 52 percent of the
eligible heroin users, although there was substantial variation by site and
gender (see table 3). In addition, two separate interviews were completed
with about 63 percent of the eligible heroin-and-powder users and 57
percent of the eligible heroin-and-crack users. Table 3 summarizes eligible
arrestees' participation in the study. These differential rates are at least
partially explained by the fact that interviewers were instructed to attempt
to interview crack users first, followed by heroin users and powder users.
Because previous studies provided an overview of heroin markets, this
research emphasized interviewing crack users.[7]
The procurement interview consisted of approximately 100 questions and
collected data on both drug purchase patterns and drug use patterns. The
purchase pattern questions addressed such issues as the proximity of
purchases to the buyer's home and neighborhood; the relationship between
buyer and seller; frequency of purchases; source of income for drug
purchases; and the presence of firearms during drug transactions. Use
pattern questions focused on the amount of narcotics typically used;
frequency of use and cessation; and polydrug use patterns.
Two-thirds (1,620) of the interviews were conducted with adult males;
785, with adult females. Among juvenile participants, 49 were boys and
16 were girls.[8] Of all these individuals, 350 completed an interview only
for powder, 821 only for crack, and 471 only for heroin; 242 completed
separate instruments for both powder and heroin, and 172 completed
separate instruments for both crack and heroin. (These latter two groups
are often referred to as combination heroin users in the text.) Because
some respondents completed more than one form, there were actually
2,470 completed interview forms -- 993 for crack, 592 for powder, and
885 for heroin. Table 4 summarizes participation in the study by site.
Table 5 breaks this information down by gender and adult/juvenile status,
while table 6 contains data on racial categories. 
Profile of Users
Age
Table 7 summarizes information regarding the age of individuals
participating in the study (excluding juveniles). In general, powder users
were the youngest group (although not in all sites). Also, combination
heroin users were generally the oldest. Some of the differences in average
age were statistically significant at the site level. Age differences can have
practical significance, in that they may signal different initiation rates. For
example, recent initiation into crack use has been relatively low in a
number of DUF sites, resulting in an aging of the crack-using cohort in
those cities.[9]
Living Arrangements
Primary living arrangements of the respondents varied by site. A majority
or strong plurality of Chicago and Manhattan residents, regardless of their
drug use category, reported living in an apartment in the 30 days prior to
arrest. Overall, more than 40 percent of the users of each drug reported
living in an apartment, although this distribution is affected by the
concentration of apartment dwellers in Chicago and Manhattan. In
contrast, a majority or strong plurality of respondents in Portland, San
Antonio, San Diego, and Washington, D.C., reported living in a house. At
the city level, heroin users were the most likely to report living in public
housing, although the speci-fic type of heroin use (heroin only, heroin and
powder, or heroin and crack) that was prevalent among residents of public
housing varied from city to city.
Crack users typically reported living in shelters more frequently than other
drug users at the city level. Overall, 7 percent of crack users lived in a
shelter for most of the 30 days prior to arrest, including 11.5 percent in
Washington and 8.5 percent in Manhattan. In Chicago and Portland,
combination heroin users reported living in shelters more frequently than
crack users. Typically, however, such situations involved relatively small
numbers of respondents. In the nonqualifying DUF population (that is,
those who did not report using these drugs in the 30 days prior to arrest),
less than 2 percent reported living in shelters immediately before arrest. 
Similar findings were evident with respect to those respondents living on
the streets. That is, crack users typically reported being on the streets more
frequently than other drug users, although the rates for combination heroin
users were generally comparable. Overall, San Diego reported the highest
street-living rate (16.5 percent across drugs), a finding that may be largely
attributable to the area's benevolent climate. The rate of street living for
procurement study participants was substantially higher than the rate for
the general DUF population. Between 3 and 4 percent of the nonqualifying
DUF respondents reported living on the streets prior to their arrest,
compared to rates that were three and four times higher in this study
population. Table 8 summarizes issues related to living arrangements. 
Sources of Income
A sizeable fraction of the respondents reported that their main source of
income was either full-time or part-time work. San Antonio reported the
highest rate of employment (either part-time or full-time) across drug use
categories, 65 percent. Manhattan reported the lowest rate of combined
full- and part-time work, less than 28 percent. Generally, at the site level,
powder users were most likely to report work as the primary source of
their income (the specific percentages varied by city). Table 9 pre-sents
information relating to income sources by site and drug used.
Combined across drug categories, more Manhattan participants reported
public assistance as their largest single source of income (more than 32
percent) than all forms of work combined (less than 28 percent). In
contrast, about 11 percent of the San Antonio respondents reported public
assistance as their primary source of income. Across cities, powder users
generally reported public assistance as their primary income source much
less frequently than other drug users. Crack, heroin, and combination
heroin users reported public assistance as their primary income source
with greater frequency than powder users. 
A much larger fraction of women (31 percent) mentioned public assistance
as a main source of income than of men (14 percent). In no city did males
report public assistance as a main source of income more frequently than
females. Manhattan had the highest percentage of both males (19 percent)
and females (37 percent) reporting public assistance as their primary
source of income, while San Antonio had the lowest rate for males (4
percent) and Portland for females (19 percent).
A large fraction of the respondents generated their main income from
illegal activities. The highest rate of participation in illegal activities to
provide primary income was found in Manhattan and Chicago (24 percent
across drug categories) and the lowest in Washington, D.C. (less than 8
percent). Prostitution was not counted in the "other illegal" category, but
was counted in "other." Among females, about 20 percent of combination
heroin-and-powder users and 10 percent of all other drug users reported
deriving the largest share of their income from prostitution. 
Table 10 shows average monthly incomes by primary source category.
That is, it shows the average total income for the 30 days preceding arrest,
with the respondents grouped according to the primary reported income
source. These data are limited to Manhattan because it is difficult to
reliably combine data across sites. Even though Manhattan is not
necessarily representative of the other sites, it offers the advantage of
having more data than any other study location. The results should not be
generalized to other sites. 
Approximately 20 percent of the respondents reported no legal income; 55
percent reported no illegal income; and the balance reported a combination
of legal and illegal income. In Manhattan, those who reported welfare and
Supplemental Security Income (SSI) as their major financial resource had
an average monthly income of $514 prior to arrest, ranging from $607 for
heroin-and-powder users to $395 for powder users. Not all of that money
came from welfare and other public sources; rather, that was the average
total income for people who reported public assistance as their primary
source of income. If median, rather than average, incomes were used, the
amounts would drop, but the relative ranks would remain the same.
Arrest Charges
Participants in the procurement study were more likely than
nonparticipating DUF respondents to have been arrested on drug charges
(see table 11). For many nondrug offenses, the percentages were
approximately equal in the two groups. However, both violent and
weapons offenders were represented less frequently in the procurement
study than in the DUF study. The higher rate at which drug offenders were
represented in the procurement study suggests that recent drug use is
concentrated among drug offenders. An examination of recent DUF
statistics confirms that drug offenders (and those arrested on prostitution
charges) are more likely than most other arrestees to test positive for
cocaine and other drugs.[10] A likely explanation for the
overrepresentation of drug offenders in the procurement study may be that
recent use is found disproportionately among drug offenders and the study
screened for recent use. Since drug offenders participated in the
procurement study with disproportionate frequency, it is important to
examine whether such users have market participation characteristics that
distinguish them from other users. Thus, data for drug offenders and
nondrug offenders are reported separately in some analyses.
Race and Drug Use
Tables 12 and 13 illustrate the intersection of race and drugs in different
ways. Table 12 shows percentages by race within drug use categories.
Table 13 shows percentages by drug use category within race. Both tables
are divided into drug offender and nondrug offender categories. This
division demonstrates the relative stability of drug use across offense
patterns and partially adjusts for drug arrest practices that may
disproportionately affect certain groups in the cities.
Table 12 reveals that blacks generally constitute a majority or plurality of
users within all drug cate-gories. For example, approximately 73 percent
of crack-using drug offenders and 72 percent of crack-using nondrug
offenders in Manhattan were black. Table 12 also reveals that whites'
largest share of a drug category's population was generally among heroin
users (however, in Portland, whites were disproportionately represented
among powder cocaine users as well). Excluding Chicago (because of the
small number of whites interviewed), whites constituted anywhere from
more than 75 percent of the heroin population (Portland) to 16 percent
(Washington, D.C.). 
Table 13 reveals that drug use is relatively evenly spread across powder,
crack, and heroin among both whites and Hispanics. That is,
approximately equal proportions of whites can be found among crack,
powder, heroin, and combination users; a similar pattern holds for
Hispanics. Many deviations from this general pattern are shown in table
13, but these are usually accompanied by a small number of observations. 
In contrast, table 13 reveals that drug use among blacks is highly
concentrated in crack. In every city but Chicago, more than 50 percent of
the blacks interviewed reported that they used crack. Generally, heroin
was the drug next most frequently reported by blacks. The concentration
of black drug use in crack appears regardless of whether the individual
was arrested on a drug offense or a nondrug offense. Thus, even if arrest
practices for crack unduly result in excess arrests of blacks on crack
charges, the high rate of crack use among black nondrug offenders
indicates that something other than drug arrest practices must be invoked
to explain drug use patterns among black arrestees. 
Purchase Patterns
Buyer-Seller Relations
Heroin users and powder cocaine users were more likely to report using a
main source -- one seller from whom the buyer regularly or usually
purchases drugs -- than were crack users. More than 47 percent of powder
users and nearly 46 percent of heroin users reported having a main source,
compared to less than 36 percent of crack users. Site variations on use of a
main source were evident. Ignoring combination users, crack users were
the least likely to rely on a main source in three of the six sites. In general,
respondents in Chicago, Manhattan, and Washington, D.C., were the least
likely to use a main source, regardless of the drug they used. In Portland,
powder cocaine purchases were slightly less likely to involve a main
source than were crack cocaine purchases. The frequency with which
combination drug users used main sources varied with the specific drug.
For example, heroin-and-crack users in Manhattan had main sources for
heroin in nearly 54 percent of the cases, but for crack in less than 43
percent of the cases. Table 14 presents findings about the use of a main
source at the site level.
Black drug users participating in this study were generally least likely to
use a main source for obtaining their drugs (see table 15). Exceptions were
found, but these were typically in situations with a limited number of
observations. (After stratification by city, use of main source, drug, and
race, the cell sizes were often too small for significance testing.) In most
cases, the rate of Hispanics who relied on main sources fell between the
rates of blacks and whites; however, the individual site samples included a
relatively small number of Hispanic participants. Table 15 does not report
on combination heroin users, because of limited data in these categories. 
Respondents who reported having a main source were asked to identify the
ethnicity of their main source. Table 16, which is a contingency table,[11]
illustrates the interdependence of buyers' and main sources' ethnicity for
crack. (Because of the complexity of the table and the relatively small
number of observations for drugs other than crack, only crack sources are
presented in table 16.) The top line in every cell reports the observed
number of main sources by ethnicity; the middle row reports the expected
number of main sources by ethnicity (calculated from the row and column
percentages multiplied by the cell population); and the last row reports the
difference between the observed and expected, adjusted by the variation in
the data. Negative values for adjusted residuals indicate that there were
fewer observations in the cell than if the row and column variables were
independent. If the cumulative deviations of expected values from
observed values are large, then the hypothesis that the race of the buyer
and the race of the main source are independent of each other can be
rejected. In the case of crack, the hypothesis of independence can be
rejected for each site. In other words, it is likely that there is an interaction
between the race of the buyer and the race of the main source, and that the
differences between observed and expected values are not due to chance.
To take some examples from table 16, the intersection of black main
source with black buyer in Manhattan shows that 42 black crack users
reported a black main source, whereas 39.1 would have been expected if
no interaction had existed and independence had prevailed. Thus, there
was a slightly disproportionate tendency for blacks to buy crack from a
black main source in Manhattan. Reading down the diagonal for each site,
it is evident that a tendency to buy disproportionately from a person of the
same race existed in most sites for most racial groups (these are shaded in
black in table 16). That is, the adjusted residuals down the same race
diagonal are usually positive. Some racial or ethnic groups in some cities
disproportionately reported main sources of a different ethnicity, although
this occurred only in cases with small numbers of observations.
Manhattan's powder cocaine markets and Chicago's heroin markets also
showed that buyers were disproportionately likely to report using a main
source of their own ethnicity. All other markets had insufficient
observations to model the relationship.
Dealer Networks
Crack users reported having more extensive dealer networks than powder
users or heroin users.[12] The reported dealer structure for crack held up
across all sites; that is, in no site did the average number of powder or
heroin dealers exceed the average number of crack dealers. Note, however,
that the differences in means did not test significantly across any pairwise
combinations in any of the sites. This is primarily because the data on
dealers known are not normally distributed; rather, they are skewed with a
long righthand tail. When the dealer data are log transformed, the
distribution is approximately normal and many pairwise differences are
significant. Table 17 reflects log-transformed data. San Antonio and
Manhattan respondents generally reported smaller dealer networks than
the other cities; Chicago and San Diego respondents, medium-sized
networks; and Portland and Washington, D.C., respondents had larger
networks.
Location of Purchases
Most crack and heroin purchases were reportedly made outdoors. For both
drugs, a majority of respondents in all sites (except the Portland crack and
San Diego heroin markets), reported making their purchases outdoors. In
contrast, powder cocaine users typically reported making purchases
outdoors with less frequency than crack and heroin users. Weather did not
appear to be a significant factor in determining the market's predominant
structure. Cities with a warmer climate, such as San Diego and San
Antonio, exhibited trends that were similar to the overall trend -- even in
these two cities, crack purchases tended to be made outdoors and powder
purchases indoors. Only in Portland did a majority of crack users (52.5
percent) report typically making crack purchases indoors. Two cities --
Chicago and Washington, D.C. -- can be characterized as having primarily
outdoor drug markets. In those cities, more than 70 percent of all
transactions for most drugs were reported as typically occurring outdoors.
Table 18 provides a summary of outdoor purchases, by drug type and site.
As shown in table 19, crack users were generally likely to report making
their purchases in their own neighborhoods. (Respondents used their own
definitions of "neighborhood" when answering the question.) In five of the
six sites, a majority of crack users reported usually making purchases in
their neighborhood, compared to a majority of heroin users in four of the
six sites and a majority of powder users in two of the sites. The frequency
of crack purchases near the home ranged from 73.4 percent in Manhattan
to 47.5 percent in Portland. 
Of purchases that took place indoors, the overwhelming majority occurred
in a residence. More than 85 percent of crack respondents and 88 percent
of heroin respondents usually made indoor purchases in residences. For
crack, residence-based purchases ranged from 100 percent in San Antonio
to 78 percent in Manhattan. For heroin, residence-based purchases ranged
from 100 percent in San Antonio and Washington, D.C., to 71 percent in
Manhattan. In contrast, powder cocaine transactions, while still
predominantly occurring in residences, were more likely than heroin or
crack transactions to occur in businesses. Overall, about 22 percent of
powder respondents reported usually buying at a place of business,
ranging from a low of 12 percent in San Diego to a high of 38 percent in
Chicago. Manhattan, Chicago, and Washington reported the highest rates
of making purchases in abandoned buildings, at least for heroin-only and
crack-only purchases. About 10 percent of Manhattan respondents
reported regularly buying crack and heroin in abandoned buildings, as did
9 percent of Chicago respondents and 7 percent of Washington
respondents. 
By race and ethnic group, Hispanics and blacks were more likely than
whites to report that they usually made their purchases outdoors. This
result usually held across drug type and across sites, except in situations
where there were a small number of observations. Hispanics and blacks
were also more likely than whites to report making the majority of their
purchases in their own neighborhoods (again, across drug types and sites).
Failed Transactions
Respondents were asked to recall if they had unsuccessfully attempted to
purchase drugs in the past year. The fraction of arrestees who had at least
one failed transaction varied substantially by drug and by city. Overall,
crack users (excluding combination users) were typically the most likely
to have reported a failed transaction at the site level (see table 20).
Generally, large fractions of users in Manhattan failed to complete
purchases, although other sites had higher percentages for individual
markets. More than 40 percent of crack users in Manhattan and San Diego
and more than 55 percent in San Antonio, for example, reported being
unable to buy crack at least once during the last year, despite having the
willingness and the money to do so. 
Those who reported a failed transaction were asked to recall why they
were unable to complete the transaction. The question was designed to get
them to recall a situation when external circumstances (other than their
own lack of resources) limited their ability to purchase drugs. Interviewers
did not offer answers to the participants, but rather coded responses into
the best-fitting category. Respondents frequently ascribed their failure to
complete a transaction to their inability to locate a dealer or to the dealer's
lack of supply (see table 21, which excludes combination users). In
Manhattan, however, where police were aggressively enforcing
quality-of-life statutes against panhandling, drug dealing, fare beating, and
other crimes, 64 percent of crack users, 55 percent of heroin users, and 38
percent of powder users reported police activity as a factor in their failure
to obtain drugs. In contrast, the city with next highest mention of police
activity was Chicago, where 18 percent of heroin users and 17 percent of
crack users cited such activity as a factor. Respondents in Washington,
D.C., mentioned police activity even less often: no respondents in the
powder market, only one (2.9 percent) in the crack market, and three (16.7
percent) in the heroin market. It should be noted, however, that the overall
percentage reporting failed transactions was generally no higher in
Manhattan than in the other study sites. Thus, while police in Manhattan
were disproportionately named as a factor among the subset of failed
transactions, it cannot be concluded that police activity caused the subset
to be any larger in Manhattan than in other study sites. 
Another factor to note in table 21 is that a small fraction of crack and
heroin users reported high prices as the reason for their failed transactions.
However, fairly large fractions of powder users offered price as a
motivation for failed transactions. Data on prices and purity indicated that
while a majority of crack users thought prices were stable, a sizable
minority perceived prices to be increasing. Thus, even though some
respondents thought crack prices were increasing, the increases were not
cited as a barrier to purchasing the drug. This information suggests that
powder users may be more sensitive to price changes than either heroin
users or crack users. 
Purchase Frequency
Respondents were asked if they had purchased drugs in the week prior to
their arrest and interview. A large majority of respondents in each site
indicated that they had purchased drugs in the previous week (see table
22). The low was in San Diego, where 63 percent of the participants
reported buying drugs, and the high was in Manhattan where nearly 91
percent reported making a purchase in the 7 days before arrest. Overall,
Manhattan generally had the highest percentage of arrestees reporting
recent purchases (across drugs); San Diego and Portland had the lowest.
By drug category at the site level, powder users were usually less likely
than others to report having made a recent purchase.
Among those reporting having purchased drugs in the 7 days prior to
arrest, heroin users appeared to have made the greatest number of
purchases (see table 23). In most sites, heroin users (or combination heroin
users) had the highest number of mean weekly purchases. In San Diego,
however, while combination heroin users reported the highest number of
mean weekly purchases, heroin-only users reported the second lowest
number. In Manhattan and San Diego, crack users averaged more
purchases than heroin users in the week preceding their arrest. Crack users
typically reported more weekly purchases than did powder users at the site
level, but the data were not statistically significant. Only in Portland did
powder users report more weekly purchases than crack users. 
Guns and Drug Purchases
Respondents were asked if they carried a firearm while purchasing drugs
during the month preceding arrest. In four of the six sites, crack users were
the least likely to report carrying a weapon while obtaining drugs. In these
sites (Chicago, Manhattan, San Diego, and Washington, D.C.) between 3
and 6 percent of crack users reported carrying a gun in the 30 days prior to
arrest. In San Antonio and Portland, heroin users were less likely than
crack users to report carrying a gun.
Overall, San Antonio arrestees reported the highest rate of carrying guns
(12.4 percent).  More than 8 percent of the respondents from each type of
drug market in San Antonio reported carrying firearms. In contrast,
Washington had the lowest overall rate, with only 4.1 percent of arrestees
in that city reporting that they had carried a gun during drug purchases in
the 30 days before arrest. 
In general, larger fractions of powder users reported carrying firearms than
users of other drugs, particularly when excluding combination users. In
three sites (Chicago, San Antonio, and San Diego), combination users
were more likely to report carrying a gun than powder users, but these
findings were based on fewer than 20 observations for the combination use
categories. Several factors may plausibly explain the differences in gun
possession across drug markets. First, powder cocaine users are more
likely to make their purchases indoors (table 18) and more likely to travel
(table 19); both activities may increase the perceived need to carry a
firearm. Second, powder users may have greater cause to protect
themselves if they more frequently buy larger quantities and carry more
cash. On the other hand, powder users are also more likely to have a main
source from whom they regularly purchase drugs; such a relationship
would probably reduce their inclination to carry a weapon. In contrast,
crack users may be more reluctant to admit carrying a firearm than other
drug users because of the severe penalties associated with possession of
small amounts of crack and the fear that a gun charge could lead to even
worse legal consequences. 
Use Patterns
Three-Day Use
Participants in the procurement study were very likely to test positive for
drugs. Respondents to the crack addendum were more likely to test
positive for cocaine than respondents to the heroin or powder cocaine
addenda were to test positive for those drugs. The DUF interview is
accompanied by a drug test that is capable of detecting recent drug use
(within approximately 3 days). Overall, more than 90 percent of those
completing a crack interview tested positive for cocaine, and more than 80
percent of those completing a heroin interview tested positive for opiates.
Generally, combination heroin-and- crack users were more likely to test
positive for cocaine than for opiates, while combination
heroin-and-powder users were about equally likely to test positive for
opiates and for cocaine. These findings are detailed in table 24. 
For comparison purposes, table 25 shows the percentage of positive drug
tests for the corresponding general DUF populations in the study sites. In
general, while relatively large fractions of the general arrestee population
tested positive for drugs, the procurement study population was
substantially more likely to have consumed drugs recently. Note that table
25 classifies DUF respondents only by drug test results, not by completed
interview instruments; thus, this table has no category for crack.
Daily Use
In each site, heroin users were more likely than powder or crack users to
describe themselves as daily users. In addition, combination heroin users
(heroin with either crack or powder) reported being daily users of both
drugs with greater frequency than powder-only and crack-only users. In
contrast, powder users were less likely than any other respondents to
consider themselves daily users. These findings are detailed in table 26.
Those who identified themselves as daily users were asked to report the
number of times they used the drug in an average day. Generally, cocaine
users -- both powder and crack -- reported a larger number of daily uses
than heroin users (see table 27).  
Among those who did not define themselves as daily users, a different
pattern emerged. These individuals reported less use per week (on
average) than daily users reported per day (see table 28). Remember,
however, that those who considered themselves daily users (including
large fractions of crack, heroin, and combination users) are not included in
table 28. 
Duration of Use
Information on the duration of drug use provides valuable insights into
drug problems. Changes in the frequency of use, for example, may
indicate intensification of an epidemic, concentration of use, or diffusion
of use into a different pool of users. Similarly, differences in use patterns
across drugs may point to the severity of a drug's addiction profile. The
procurement interview asked arrestees about a variety of different aspects
of drug use in an effort to discern some of these distinctions.
Perhaps not surprisingly, heroin users reported the longest periods of
sustained use (see table 29). In the 90 days preceding arrest, larger
fractions of heroin users than of powder or crack users reported daily or
near-daily use. In addition, large fractions of combination heroin users
reported daily or near-daily use for both heroin and cocaine. These
findings suggest that few of the heroin respondents in the sample, relative
to powder-only and crack-only users, have a casual habit and that polydrug
users may have complicated drug use patterns. 
Cessation of Use
Drug cessation periods can also be informative, as they may indicate what
disrupts drug use patterns. Powder users appear to be the most likely to
have use patterns that include extended periods of nonuse. From
one-quarter to two-thirds of the powder users reported a monthlong period
of nonuse in the 90 days prior to arrest, compared to one-quarter to
one-third of crack users and less than one-quarter of heroin users. From
table 30, it is clear that only a relatively small fraction of heroin users have
use patterns that include extended (1 month or longer) periods of nonuse.
Users were asked to explain why they went as long as they did without
using drugs. Among powder, crack, and heroin users in Manhattan, 57
percent of powder users reported that they were not daily users and that
their regular consumption pattern included periods of nonuse. (See table
31. Findings in other sites were generally comparable but are not
presented.) The next most common motivation among powder users in
Manhattan was "could not afford" (9.5 percent), followed by "wanted to
change" (8 percent). Similar patterns were found among crack users and
heroin users; 27 percent of the former and 31 percent of the latter reported
that their regular patterns included periods of nonuse. The next most
common responses among crack users for periods of nonuse were "could
not afford" (20 percent) and "tired of [the drug] life" (19 percent). Among
heroin users, the most frequent explanations after regular use pattern were
"in treatment" (24 percent) and "jailed/incarcerated" (12 percent). 
Among the data that stand out in table 31 is that no arrestees cited lack of
drug availability as a factor in determining their use patterns, and only one
crack arrestee reported drug testing as a factor influencing periods of
nonuse. Six percent of crack users and 12 percent of heroin users cited jail
and incarceration as affecting their use patterns. 
Conclusions and Implications
Drug User Profile
Evidence from the drug procurement study indicates that respondents face
multiple risks in their lives. They reported relatively high rates of living on
the streets and in shelters, even in comparison to the general arrestee
population in their communities. In addition, substantial fractions of
respondents reported that public assistance or drug dealing and other
illegal activities were their primary form of income. The findings also
suggested that while study participants were likely to report frequent drug
use and very likely to test positive for drug use, they were also in contact
with institutions that provide other services, such as temporary shelter,
permanent housing, and financial assistance. Drug-using arrestees' contact
with such institutions should be studied carefully from the perspective of
how these institutions might appropriately and effectively use their
resources to address the problems of substance abuse. 
Drug Purchase Patterns
Crack was more likely to be purchased under circumstances that exposed
the buyers (and sellers) to law enforcement risks. A typical crack user in
the procurement study made numerous purchases in a week, although not
as many as a typical heroin user. Crack and heroin purchases were both
very likely to take place outdoors, where they were more visible (table 18).
In addition, crack buyers were less likely to buy from a main source than
were other drug users (table 14) and more likely to have a large circle of
dealers from whom to buy. These large networks could introduce
additional exposure risks. There may also be an interaction effect; that is,
the combination of buying outdoors from a stranger relatively close to
one's residence (crack markets) poses different hazards than buying
outdoors from a stranger or main source in a location farther from one's
residence (heroin markets). These elements, in isolation or combination,
may expose individuals participating in crack transactions to greater risk
than individuals participating in transactions for other drugs. A cumulative
effect also results in elevated risk of arrest for crack users: The relative
size of the heroin and crack markets means that there are more crack
transactions than heroin transactions to observe. Cumulatively, then, these
characteristics may expose crack users to greater visibility and greater risk.
The issue of risks and exposure has particular relevance for the black
arrestee population. Black respondents were more likely than whites and
Hispanics to participate in crack markets in ways that apparently increased
risks. For example, if law enforcement officials focus their efforts against
outdoor crack markets that are concentrated in certain neighborhoods -- a
reasonable policing strategy -- this approach may disproportionately affect
blacks. The disproportionate impact will arise because blacks are more
likely than whites and Hispanics to make their purchases outdoors and are
more likely to make them in their own neighborhoods. Whites and
Hispanics, on the other hand, are more likely to travel away from their
neighborhoods to make their purchases and are more likely to make them
indoors. As a result, drug transactions conducted by blacks may be more
visible to law enforcement, thus subjecting blacks to greater risk for
drug-related arrests. 
Drug Use Patterns
Participants in the procurement study were very likely to test positive for
drugs. In addition, substantial fractions of heroin and crack users were
likely to describe themselves as daily or dependent users. Among those
describing themselves as daily users, most respondents reported
consuming drugs more than once daily. Respondents also reported a
variety of motivations for periods of nonuse. Powder cocaine users were
most likely to report that their regular use pattern included periods of
nonuse, but heroin and crack users also reported such patterns of
intentional nonuse. In addition, substantial fractions cited other reasons for
nonuse, including the cost of drugs, being tired of the consequences of
drug use, and being in treatment programs or in jail. 
These findings may be encouraging, because they indicate that service
providers may have a window of opportunity for intervention; they also
identify influences over drug use patterns that policy-makers may be able
to manipulate or supplement. These findings suggest that a more careful
and detailed examination of the factors influencing arrestees' drug use
patterns would be beneficial.
Policy Implications
Analysis of the findings reveals that the powder, crack, and heroin markets
differ substantially from one another in a variety of ways, including
purchase and use practices. To the extent that drug-using arrestees are a
particular problem in many communities, the findings also suggest that
detailed information about local drug habits and patterns would be a
valuable tool for law enforcement authorities, service providers, and
policy-makers. Further refinements of the interview instrument, for
example, could provide information that would be useful for local policy
evaluations, impact analyses, and prevalence monitoring. 
The data also suggest that it is possible to tap into the DUF pool to explore
motivations for drug use and policy interventions that interrupt drug
markets. A more specific set of questions could explore such critical
factors as deterrence, substitution of one drug for another, and the
interaction between policing operations and perceived need for treatment
services. Of particular interest would be whether there are differences in
deterrence and cessation motivations across drug markets. For example,
the findings presented here suggest that powder users, when they
temporarily stop using cocaine, are motivated by factors over which they
generally have more control, including the perceived need to improve their
circumstances. Crack and heroin users, in contrast, are more likely to be
motivated to stop drug use by factors associated with the consequences of
consumption. Given these apparent differences in motivations, it should be
possible to design questions to explore what set of deterrents would work
against what types of users.
Notes
1. Mark A.R. Kleiman and Ann Marie Rocheleau, 1993, "Measuring
Heroin Availability: A Demonstration Program," report prepared for the
Office of National Drug Control Policy by BOTEC Analysis Corporation,
September; David A. Boyum and Ann Marie Rocheleau, 1994a, "Heroin
Users in Three Cities," report prepared for the Office of National Drug
Control Policy by BOTEC Analysis Corporation, August; David A.
Boyum and Ann Marie Rocheleau, 1994b, "Heroin Availability in New
York, San Diego, and Chicago," report prepared for the Office of National
Drug Control Policy by BOTEC Analysis Corporation, August.
2. The DUF program is now known as the Arrestee Drug Abuse
Monitoring (ADAM) program. It is being expanded to 75 cities
nationwide.
3. As a followup to the crack, powder cocaine, and heroin addendum, NIJ
awarded a DUF Challenge Grant to the San Diego Association of
Governments (SANDAG) to conduct similar research into
methamphetamine markets. Using a similar interview instrument,
SANDAG began collecting data in five sites (Los Angeles; Phoenix;
Portland, Oregon; San Diego; and San Jose) in October 1996. Findings
from the methamphetamine study will be available in 1998.
4. The 10 drugs are cocaine, opiates, marijuana, PCP, methadone,
benzodiazepines, methaqualone, propoxyphene, barbiturates, and
amphetamines. Powder cocaine cannot be distinguished from crack
cocaine in the test. Samples that test positive for amphetamines are
subjected to gas chromatography analysis to eliminate false positives
caused by use of over-the-counter medications. 
5. Note that these figures understate the number of individuals eligible and
overstate the completion rate. Respondents screened into the procurement
study by self-reporting drug use in the 30 days prior to arrest; however,
self-reported data on drug use consistently understate actual use. 
6. The reporting convention for the tables in this document parallels the
number of forms that the individual completed. For example, individuals
completing only a powder cocaine interview are reported under "powder"
in the tables, while those completing both heroin and powder cocaine
interviews (or heroin and crack interviews) are reported under "heroin and
powder" (or "heroin and crack"). Where drug-specific, rather than
individual-specific, factors are of interest, the data from the "heroin and
powder" and "heroin and crack" categories are reported separately. Many
of the tables have a variable name printed in the upper left corner. The
interview question corresponding to the variable can be found in the
appendix. Tables without a variable name in the upper left corner are
either summary tables or are derived from the main DUF instrument.
7. Kleiman and Rocheleau 1993; Boyum and Rocheleau 1994a; Boyum
and Rocheleau 1994b.
8. Given the small number of juveniles participating in the study, they are
dropped from all analyses and only included in the summary participation
tables in this section (tables 1B6). 
9. Andrew Lang Golub and Bruce Johnson, 1997, Crack's Decline: Some
Surprises Across the United States. Washington, D.C.: U.S. Department of
Justice, National Institute of Justice.
10. National Institute of Justice, 1997, 1996 Drug Use Forecasting Annual
Report on Adult and Juvenile Arrestees. Washington, D.C.: U.S.
Department of Justice, National Institute of Justice.
11. Contingency means dependence, so a contingency table reflects how
one characteristic (arrayed in a row) affects another characteristic (arrayed
in a column). If the characteristics are independent of each other, then the
percentage found in any given cell should be approximately equal to the
product of the corresponding row and column percentages. If one
characteristic depends, to some extent or another, on the other
characteristic then the cell percentage will differ from the row-column
product.
12. A cluster of 101 individuals reported knowing exactly 100 dealers. In
addition, 33 respondents reported knowing more than 100 dealers from
whom they could buy. Omitting values greater than 100, one-third of
which were greater than 500, reduces the variable means but does not
change the relative rankings.
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The complete addendum coding catalog, along with separate and merged
data files, will be archived at the Inter-University Consortium for Political
and Social Research at the University of Michigan. Interested analysts can
also find complete 1995 and 1996 Drug Use Forecasting (DUF) files there.
DUF files may be useful for conducting additional analyses on differences
between addendum and nonaddendum respondents.
-------------------------------------------------------
For more information on the National Institute of Justice, please contact:
National Criminal Justice Reference Service
Box 6000
Rockville, MD 20849B6000
800-851-3420
e-mail: askncjrs@ncjrs.org
-------------------------------------------------------
You can view or obtain an electronic version of this document from the 
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