groups responsible for making policy to control drug abuse. While we will take a position on ..... circle" or "positive feedback" phenomenon. In the absence ... in the price of housing, permitting successively poorer peo- ple to live in the area.
The narcotics problem is complex and the authors endeavor to show how systems analysis and computer simulation can aid in its study. On this basis recommendations are made for community action.
Narcotics and the Community: A We present here a summary of work still in progress after a year of effort devoted to the problem of narcotics addiction and its control. While the investigation has drawn substantially from consideration of a specific ethnically and economically heterogeneous geographic region in New York City, an area of eight square miles with a population of about 180,000 persons, the processes described are believed to apply substantially to a wide range of urban and suburban environments, excluding only those of exceptional wealth or exceptional poverty. The computer model that has been developed describes the flow of numbers of people in a community through various drug use statuses: potential users, soft drug users, heroin users, addicts in the community, addicts in community care, addicts in custody; each of which is regulated by one or more associated rates of change. Other sectors of the model describe the important variables in the community that affect the rate at which people move through the various statuses. The model treats explicitly migration into and out of the community of addicts and other population subgroups, the consequences of community alarm versus inaction, crime and other visible manifestations of drug use, attitude of the community toward addiction, attractiveness of the area to pushers, as well as other important, but often elusive, forces. Computer experiments assess the probable short- and long-range consequences of each of the programs and policies that have been advocated or tried. To our knowledge this constitutes the first attempt to integrate and systematically manipulate the large and unwieldy body of scientific knowledge and knowledgeable opinion relevant to this problem. The information used in constructing the model has been gathered from a variety of sources including a critical review of the literature, an area study of an urban community, and interviews with treatment program directors, addicts, ex-addicts, research scientists, teachers, parole officers and other informant groups.' The purpose of this investigation is to provide knowledge of use to a variety of groups responsible for making policy to control drug abuse. While we will take a position on some issues, our intention in this paper is not primarily to advocate a particular policy, but to describe the work we have done and to show how it can contribute to the understanding and evaluation of any proposed policy.
Why Model? Construction of a computer model begins with an effort to understand the system of forces that has created a problem and continues to sustain it. Relevant data are gathered from a variety of sources, including published lit-
System Stimulation Gilbert Levin, Ph.D.; Gary Hirsch, S.M.; and Edward Roberts, Ph.D.
erature, informed persons (experts, practitioners, victims, perpetrators, etc.) and specific quantitative studies. As soon
as a rudimentary measure of understanding has been achieved a formal model is developed. This model is then exposed to criticism, revised, exposed again and so on in an iterative process that continues as long as it proves to be useful. Just as the model is improved as a result of successive exposures to people, a successively better understanding of the problem is achieved by the people who participate in the process. Their intuition about the probable consequences of proposed policies frequently proves to be less reliable than the model's meticulous arithmetical approach. This is not as surprising as it may first appear. The behavior of any system in which as many as a hundred or more variables are known to be relevant and believed to be related to one another in various nonlinear fashions is complex far beyond the capacity of intuition and, incidentally, even further beyond the capacity of formal mathematical analysis. Simulation is one of the most effective means available for supplementing and correcting human intuition. A computer simulation or model of the variety described here is a powerful conceptual device that can increase the role of reason at the expense of rhetoric in the determination of policy. A model is not, as sometimes supposed, a perfectly accurate representation of reality that can be trusted to make better decisions than people. It is a flexible tool that forces the people who use it to think hard and to confront one another, their common problems, and themselves directly and factually. A computer model differs only in complexity, precision and explicitness from the informal subjective explanation or "mental model," that men ordinarily construct to guide their actions toward a goal. It is an account of the total set of forces that are believed to have caused and to sustain some problematic state of affairs. Like the informal mental model, it is derived from a variety of data sources including facts, theories, and educated guesses. Unlike the mental model it is comprehensive, unambiguous, flexible, and subject to rigorous logical manipulation and testing. The flexibility of a model is its least understood virtue. If you and I disagree about some aspect of the causal structure of a problem, we can usually in a matter of minutes run the NARCOTICS AND THE COMMUNITY
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model twice and observe its behavior under each set of assumptions. I may, on the basis of its behavior, be forced to admit you were correct. Very often, however, we will both discover that our argument was trifling, since the phenomenon of interest to us may be unchanged by a change in assumptions. A computer model constructed and used by a policy-making group has these advantages: I) It requires policy-makers to improve and complete fully the rough mental sketch of the causes of the problem that they inevitably have in their heads. 2) In the process of formal model building, the builders discover and resolve various self-contradictions and ambiguities among their implicit assumptions about the problem. 3) Once the model is running, even in a rudimentary fashion, logical "bootstrapping" becomes possible. The consequences of promising but tentative formulations are tested in the model. Observation of model behavior gives rise to new hypotheses about structure. 4) Once an acceptable standard of validity has been achieved formal policy experiments reveal quickly the probable outcomes of many policy alternatives; novel policies may be discovered. 5) An operating model is always complete, though in a sense never completed. Unlike many planning aids, which tend to be episodic and terminal (they provide assistance only at the moment the "report" is presented, not before or after), a model is organic and iterative. At any moment the model contains in readily-accessed form the present best understanding of the problem. 6) Sensitivity analysis of the model reveals the areas in which genuine debate (rather than caviling) is needed and guides empirical investigation to important questions. If the true value of many parameters is unknown (which is generally the case in social planning) the ones that maximally affect model behavior need to be investigated first. 7) An operating model can be used to communicate with people who were not involved in building the model. By experimenting with changes in policies and model parameters and observing the effects of these changes on behavior, these people can be helped to better understand the dynamic forces at work in the real-world system.
Counter4ntuitive Effects An example illustrates the way in which logical analysis can correct dubious but intuitively appealing policies aimed at coping with the narcotics problem.2 Despite striking differences among policy advocates, there is general agreement that the social problem of heroin consists of the presence of too many addicts and of the crimes they commit to support their addiction. There is also agreement that the supply of heroin that enters this country illegally is a principal source of the problem. The implicit model may be shown as in Figure 1. An increase (decrease) in the heroin supply increases (decreases) the number of addicts, thereby increasing (decreasing) addict-related crime. Although there is agreement on this account of the problem, when it comes to potential corrective policy considerable disagreement exists. Let us consider two very different strategies which share this definition of the problem: 1) Eliminate the source of supply. The rationale is clear. If there is no heroin, there will be no heroin addicts and obviously, no addict related crime. 2) Provide a legal supply of heroin to all addicts. This policy accepts the continued 862
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presence of a population of addicts and aims at eliminating all addict-related crime. While it is generally recognized that policy I) would be difficult to implement and that policy 2) would solve only one aspect of the social problem, each of these policies has an additional deficit that is not initially obvious. Let us consider first the policy of eliminating the source of illegal heroin. The long-run effects are as indicated. In the short run, however, a drastic reduction of the heroin supply would cause an increase in addict-related crime of unprecedented proportions. It is doubtful whether society would be willing to pay this short-term cost to gain the long-term advantage. A more complete and accurate model (Figure IB) explains these consequences. A reduction in the supply of heroin per addict would increase the price. The price of heroin plays two important mediating roles omitted from the previous account of the problem structure. First, it affects the rate at which potential addicts become addicted. When the price of heroin is low, it is more accessible to the discretionary (nonaddicted) user and vice versa. Secondly, the price of heroin determines the amount of crime each addict must commit to support his habit. The causes of the differential short- and long-term consequences of a reduction in supply are implicit in the diagram. Significant time is required for the pool of addicts to change in size. Eventually, a high enough price would reduce the number of addicts and the amount of crime toward zero. The effects of a price increase on crime are much more immediate. Since a successful policy aimed at reducing supply would have a significant effect upon price long before the number of addicts was appreciably reduced, the total amount of addict-related crime would increase significantly. The severity and duration of this increase cannot be stated precisely. What is made clear by our analysis is the need to acquire reliable information on this point if a policy of vigorous supply reduction is to be considered seriously. The addition of another link in the causal chain, i.e., public resistance to policy, fills out the picture. The danger of not knowing and not disclosing fully the short-term negative effects of the policy is that public response to its actual implementation may be so negative as to force its abandonment before it has begun to work. Turning to the policy of providing heroin legally to addicts, we observe another set of undesirable counter-intuitive consequences. The intention of this policy is to destroy the illegal production-distribution system through competition. If all addicts can obtain all the heroin they need through legal channels at zero or nominal cost, it is reasoned, illegal competitors will be driven out of business. There is a serious flaw in this policy. The short-term effect of the introduction of a legal supply would be a vast increase of the total stockpile of heroin. Much of the heroin in the illegal pipeline at the time the policy went into effect would eventually reach the market place. Since addicted customers who in the past consumed the lion's share of the drug4 would have turned to the legal supply, the market would be in a state of disarray. Many individual operators would be driven out of business because of falling prices, as intended. However, those remaining would be forced to seek buyers among non-ad-
Figure 1-Several Models of the Narcotics Problem
A. Implicit Model of Addict Crime ILLEGAL HEROIN SUPPLY
-
NUMBER OF ADDICTS
ADDICT RELATED CRIME
AUMBER Of ADDICTS
RELATED CRIME
B. Price Considerations Added to Implicit Model
PRICE Of K NEROIN / s ILLEGAL HEROIN SUPPLY
ADDICTION
~~~RATE
DDICT-
ATTRITION RATE
POLICY (1) C. Further Aspects for Policy Consideration
PRIEO--,MAKTN EFFORT TO ADDICTEON
K HEROIN /t
ILLEGAL HEROIN
SUPPLY
NE USERS\
~~~RATE
ADDICTRELATED CRIME
NUMBER
OF ADDICTS
ADDICTS ON ILLEGAL
HEROIN t ADDICTS ON LEGAL HEROIN
dicts. Low prices and more aggressive marketing would result in a significant increase in the number of new addicts.5 The illegal supply of heroin, which was originally intended principally to satisfy the needs of existing addicts and only secondarily to increasing the total number of addicts, would be diverted entirely to the latter purpose. The shortcoming of this policy is that while it would reduce addict-related crime, it might significantly increase the total number of addicts. Figure IC illustrates this causal structure. Policy (2) reduces crime by drawing addicts out of the market. It thereby also reduces at least temporarily the price of illegal heroin, thus increasing the addiction rate. This latter effect is amplified by an increase in marketing of heroin to new users, a response to falling prices. In the authors' opinion, zealous application of either policy (1) or (2) would probably worsen the problem. One or another of several **intermediate" policies appear to be more promising, as indicated later in the paper. The principal intent of this extended example is to demonstrate how logical analysis of the general character
POLICY (2)
permitted by computer simulation can reveal facets of the narcotics problem that are not immediately apparent to intuition. In an actual rather than an anecdotal simulation, the computer allows a vastly increased number of variables to be considered and provides a more accurate forecast of their behavior over time.
Model Structure There is no way in ordinary language to describe a computer model precisely. The model consists of some 350 statements about the causal structure of the narcotics problem written in the DYNAMO compiler language.6 This prose account of the model almost inevitably will obscure and oversimplify the very process of model representation that the special purpose DYNAMO language was designed to clarify. The best way to understand the model is to use it. DYNAMO is designed for use on a remote terminal. The user, seated at a teletypewriter terminal, engages in a NARCOTICS AND THE COMMUNITY
863
Figure 2-Overview of the Narcotics Problem A. Macro Model of Drug Addiction and the Community
COMMUNITY CHANGE
EX-A METHADONE
B. Total Person Flow
AO IN M ONSE
responsive "'conversation" with the model. Typically he will first summon and run the model in its most recently edited form. The printer then quickly produces a time plot, for any specified period, of the variables of interest to the user. The user inspects the time plot, discovering that some of the variables exhibit behavior he expected and that others do not. Why not? To answer this question he inspects the equations or "structure" of the model, searching for the assumptions that produced the surprising behavior. He may find a parameter that seems unrealistic or a linear relationship between two variables where a nonlinear function is more convincing to him. The user then shifts to the edit mode of the interactive computer language and quickly types in the desired changes. The model is run once more and its behavior compared to the earlier run. If its behavior is no longer surprising, the user gains confidence in his subjective account of the problem. However, if the surprising behavior is still present, the user may be forced to examine his own im864
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-
plicit assumptions and change them in the direction of greater accuracy. The user demonstrates his understanding of the system structure of the problem by his ability to conduct a series of runs that exhibit a variety of modes of behavior, all of which were expected by him. This is unlikely to occur except after a lengthy series of "conversations" between user and model. The model should be seen, therefore, less as a fixed account of the narcotics problem than as a structured but flexible vehicle that permits its user to test and increase his own, understanding of the system being simulated. The causal relationships of primary importance to the model behavior are described in this section. An overview of the major causal forces (Figure 2A) and a description of the population flows through the system (Figure 2B) are presented first. Discussions of the relationships underlying the key formulations including heroin addiction (Figure 3), community attitude shift (Figure 4) and commu-
Figure 3-Heroin Addiction USER
CHIACE RATE
ADICTION RATE
FEAR OF v F~MIST DETEtRENCE.-vE FEFFECT OF DRUG \
\
\
\\11,
EDCATIN UlNCERTAINTY OF RENAIITATION
EFFICACY ANAILABILITY OF SOFT MUGS
APPEAL PSYCHOPTNOL OF 11 1|O N 1 POVERTY AND \ --.-ETHNIC STATUS DRUG -ASSOCIATED CULTURE
-
nity change (Figure 5) follow, and, within the limits stated above, give a fairly complete picture of the model's structure.
The model focuses on addicts who are functioning primarily in a community with a fixed geographic boundary. The addict population manifests itself in two major ways: creation of new addicts and commission of crimes. The addict population grows as addicts introduce their friends and acquaintances to heroin. This growth is enabled by the availability of heroin in the community required by the existing addict population, but also used to turn-on people.who later become new addicts. As the number of addicts in the community grows, more addicts are present to introduce new people to heroin and a larger heroin availability enables these introductions. The result is a more rapid growth of the addict population that accelerates as the number of addicts increases even further. This is a "vicious circle" or "positive feedback" phenomenon. In the absence of constraining forces the addict population would continue to grow without limits. Some fraction of the addicts in the community will have to commit crime in order to support their habits. The impact of crime on the community has two major facets. The first of these is community change. A growing crime rate will reduce the attractiveness of the area. The residents of higher socioeconomic status and greater mobility will migrate out into areas they perceive to have a lower crime rate. Those with less mobility are forced to remain. The yacancies left by the people who migrated out are filled by people of lower socioeconomic status for whom the crime rate of the area is the lowest that they can afford. Ethnic and racial issues often complicate the process in this way: At first upwardly mobile middle-class blacks move into the community. Their presence amplifies the tendency of whites
to leave. Rapid outmigration causes a temporary reduction in the price of housing, permitting successively poorer people to live in the area. Housing density then increases and public services are strained, thus facilitating the process of urban decay. In this way, as crime increases, the socioeconomic level of the community is driven down. Because people of a lower socioeconomic status have a higher incidence of social problems (including addiction) the in-migration brings an increasingly greater potential for new addicts that would eventually be realized in growth of the addict population. More addicts would produce more crime and the community would continue to deteriorate until its residents were of such a low socioeconomic status that they lacked the means to migrate out. The second facet of the impact of addict crime, one that constrains the positive feedback loop, is the community's response. Its immediate reaction takes the form of police action against addict criminals and pushers. Attempts to establish rehabilitation programs in the community are blocked during this phase, because residents fear that the programs will only serve to concentrate addicts in the area. Addict crime is seen to be the problem, and it is assumed that enough police effort will solve it. Usually it is only after increased police effort fails to stem the rising tide of crime, and after addiction spreads to include the children of established families in the community, that the residents will realize that addiction is a social and medical problem. They will then allow programs to be established that attempt to cope with the causes of and that seek cures for addiction. Once the community accepts the social and medical aspect of the problem, it may also permit the operation of drug education programs that deal honestly with drug use, even if they require teaching ideas contrary to the community's values. It is assumed that the effectiveness of both edNARCOTICS AND THE COMMUNITY
865
ucation and rehabilitation is influenced by the community's definition of the problem. With rehabilitation programs aimed at the current addict population, and education programs to prevent new cases of addiction, the community can begin coping with the problem of addiction itself and effectively reduce the addict population. Addict population growth, community change, and community response are the forces central to the creation of model behavior. Figure 2B shows the flow of people through the system created by the action of these forces. Here, the category "potential users" refers to nearly all of the people in the community in a vulnerable age range, perhaps between the ages of ten and thirty, who are not currently involved in the illegal use of drugs. "Users" encompasses all people who indulge in the occasional illegal use of drugs up to, and including heroin, but are not addicted to heroin and do not take up the addict's life style. ''Addicts on the street" refers to the group of people who live in the community and require at least daily shots of heroin to prevent withdrawal symptoms. This group includes addicts who live with their families and can buy heroin with money obtained from their families or from part-time jobs, without resorting to crime.7 The arrow from ''users" to 'addicts" indicates that almost all heroin addicts were previously users of other drugs (such as marijuana) but is not intended to imply a causal relationship. Addicts remain in the reference community or can migrate into or out of the community depending on the attractiveness of the area for an addict (the outside world being represented by the cloudlike symbol). They can also drop out of the addict population through death or by burning out, a process that occurs when an addict of many years standing simply becomes tired of all of the difficulties involved in being an addict and spontaneously stops taking heroin. Addicts who have been arrested and convicted spend time in prison and are released to the street or to rehabilitation programs if the programs have available capacity. Addicts also enter rehabilitation programs directly from the street. Community rehabilitation refers to therapeutic community programs, usually of a residential nature, that exist within the community itself. The Phoenix Houses in New York are an example of this kind of program. Out-ofcommunity rehabilitation includes therapeutic community programs in nearby areas as well as remote programs, such as the federal narcotics hospital at Lexington, Kentucky. Out-of-community programs are available to treat addicts, even if the community does not regard addiction as a social and medical problem. However, this condition is necessary for the existence of in-community programs. The development of in-community programs must wait for a change in the residents' view of the problem. Addicts in the re-entry process have been deemed ..rehabilitated" by either an in-community or an out-ofcommunity program, and will either successfully re-enter (remain heroin-free for a specified period of time) or return to being addicts. Addicts in methadone programs receive daily doses of methadone and are, for the most part, heroinfree. Those that remain in methadone programs for a specified period of time become ex-addicts on methadone. These people are assumed to remain indefinitely on maintenance doses of methadone. A large proportion of the addicts in the rehabilitation programs and a smaller proportion in the methadone programs will return to being active 866
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addicts before completion of the programs. The principal forces responsible for the rate at which drug users become addicts are displayed in Figure 3. There are a set of forces that promote the growth of the addict population and set of forces that retard this growth. The number of potential heroin addicts in a community depends importantly on its socioeconomic level. The appeal of heroin is also a function of the drug associated culture previously discussed, and the number of addicts already in the community. If the addict life style is seen as appealing or at least not repulsive, and there are a number of addicts available to initiate new addicts, the addict population is likely to grow. 'Psychopathology" is another causal factor implicit in the driving forces of the increase in addiction. This term refers to various individual aberrant personality patterns, such as negative identification. In this regard, a strongly negative reaction to addiction by the community will render it a more attractive outlet for antisocial tendencies. Education can act as a deterrent to addiction if it is credible and stresses the dangers of addiction without making judgments about good versus bad life styles. The availability of soft drugs in ao area may actually provide a deterrent to heroin use and addiction by making it easy to remain a soft drug user. The suppression of soft drug supplies could lead to an increase in addiction by depriving users of an alternative to heroin. Fear of arrest also deters some users from becoming addicts. Uncertainty of rehabilitation efficacy and its concomitant, fear of lifelong addiction, remain deterrents as long as rehabilitation programs are scarce and believed to be ineffective. The existence of successful programs mitigates against this effect. The time required for users to become addicts is strongly dependent on drug availability. If heroin is abundant, addicts are more likely to share it with their friends than if the drug is scarce. When there is only a small addict population in an area, local addicts will travel to other areas to get heroin and there will be very little excess heroin in the community of interest. As the addict population increases, so does the attractiveness of pushing to addicts as an alternative way of making money. Sales activities within the community necessitate inventories of drugs which increase the drug availability in the community and allow the growth of addiction to proceed more rapidly. More addicts will enhance the attractiveness of pushing, thereby increasing heroin availability and enabling the addict population to grow even more rapidly. The attractiveness of pushing is also affected by police action directed against heroin. Police action against addicts and hard drug availability are also responsible for migration of addicts into and out of the
community. Growth in the addict population has as a consequence the growth of the community's crime rate. Because crime is the primary direct impact that addiction has on the community, residents will usually define addiction initially as a crime problem and seek to combat it with a strong police response. The forces responsible for changes in community attitude toward the drug problem and the effects of this attitude are shown in Figure 4. The variable, "community definition of the problem," reflects the residents' perception of the nature of the narcotics problem. A low value indicates the belief that
Figure 4-Community Attitude
addiction is solely a criminal problem that needs to be, and can be, dealt with by sufficient police effort. A high value means that the community believes that the problem has a significant social and medical dimension, requiring treatment programs to cope with it. The community definition is affected by exposure to media and to community education programs. This attitude change will not take place, however, until the residents realize several things. First, the police solution favored by the community's initial definition of the problem must fail to stem the increase in crime caused by a growing addict population. Frustration with the police solution alone will initiate a search for alternative methods of coping with addiction. As the number of arrests increases in response to growing addiction and crime, it becomes more likely that some of those youths arrested will be familiar to residents. When narcotics arrests become more personally relevant, members of the community cease blaming the problem on ..other people". Recognition that **youths from good families" are involved in narcotics use forces people to discard an exclusively criminal view of addiction and accept some of its social and medical aspects. The pervasiveness of addiction in itself tends to persuade residents that the problem cannot be coped with by police methods alone. As these realizations develop, media and community education begin having an impact on community attitude. Eventually, if attitude change continues, the community accepts addiction as a social and medical problem with criminal manifestations rather than one of a solely criminal nature. Definition of the problem as one with a significant medical and social nature has several effects. One of these effects is the implementation of therapeutic community rehabilitation programs and methadone programs in the community. If residents feel that addiction is solely a criminal problem, attempts to establish treatment programs in the community will be vigorously opposed out of fear that the programs will merely concentrate dangerous sociopaths in the area with little benefit for the community itself. Only after the 'community develops a medical definition of the problem and drops the stereotype it has of the addict will it be willing to permit implementation of programs advocated by social agencies. Even when the community has a favorable attitude toward treatment, it may still make re-entry to
**straight" society difficult by treating the ex-addict as a criminal and not trusting him with jobs or other rewarding social contact. An ex-addict facing this bleak prospect could easily find returning to addiction to be his most desirable alternative. In order for re-entry to be facilitated, the community must see the addict as a person who was formerly sick, but who has now been "cured." A final effect of a favorable community attitude is the enabling of credible education programs. An education program in a community with a criminal definition of the problem is likely to be scare-oriented and therefore more likely to alienate youth than to dissuade them from addiction. A medical and social definition of the problem is assumed to be requisite for the acceptance of education programs that deal honestly with drugs, merely presenting the facts with a minimum of value judgments attached. The model assumes that if drug education programs are to be effective at all, they need to satisfy this condition of credibility, since most youths know too much about drugs to be fooled by scare techniques. The other major impact of addict crime, community change. is depicted in Figure 5. Some fraction of the addicts in the community will have to commit crime to be able to support their habits. As a result of the incidence of crime, some portion of its residents will decide to migrate out.8 The fraction of the residents migrating is a function of the difference between the socioeconomic level compatible with the current crime incidence and the current socioeconomic level. The concept of a compatible socioeconomic level is based on the premise that it is worth more to an individual to be in a neighborhood that is relatively free of crime. As crime increases, people living in the community no longer find their old neighborhood as attractive as it used to be, and some decide to move to an area with less crime. But outsiders who have been living in areas with a higher crime incidence would find the community of reference relatively crime-free and move in, filling the available housing. Since the new residents are of a lower socioeconomic level they are more vulnerable to the problems associated with a lower socioeconomic level. Among these social problems would be a higher vulnerability of their children to become addicts. This greater addict potential leads eventually to a
Figure 5-Community Change USER
AWICTION
CUNCE RTE
RATE
PPENTIAL UIORATIN RATE
EANS
TO
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NARCOTICS AND THE COMMUNITY
867
larger addict population which will commit proportionally more crime. The increased crime will further drive down the compatible socioeconomic level. More migration will occur, aggravating the narcotics problem and bringing about further community deterioration. As migration takes place, "community structure" is weakened. Structure is defined as the sum total of ties people have to a particular community and is assumed to be stronger among residents who have been living there for a long time. Strong community structure is assumed to retard migration. When migration is rapid, the average length of stay in the community decreases and community structure declines because residents have less time to establish ties before moving out. Deterioration of community structure permits even more rapid migration and further deterioration of structure.
Model Behavior and Preliminary Results The structure described in the previous section based upon observation of an actual community in New York City has been represented in DYNAMO and subjected to a preliminary series of simulations, which are reported below. Even though this work is preliminary in nature and has been restricted to a particular community, results to date are so striking as to warrant two broad recommendations, applicable to a wide range of communities. I) There is a need for a balanced set of programs to cope with a community narcotics problem. A total program for dealing with the problem should include sub-programs for rehabilitation, education, and police work directed at reducing heroin supply. Intensive application of any one of these programs will not be nearly as effective as the balanced use of all of them. 2) The community must perceive addiction at least in part as a social and medical problem in order for rehabilitation programs to be successfully implemented. Community education programs are required toward this end. The following series of simulations support these recommendations. The first computer simulation run shown is the symptomatic or base run against which we will compare behavior produced under the influence of remedial programs and policies. It represents the development of an extremely serious problem over a period of twenty-five years with police effort alone being used to combat the growth in addict population. The major computer outputs are shown in Figure 6. The simulation begins with an initial addict group of 150 in a community with a population of 180,000 and a youth population (vulnerable to drug use) of 51,000. About twenty per cent of these youths are occasional users of drugs. As the run begins, the number of addicts on the street (plotted by the computer using the letter A), is rising at a steady rate and total addicts on the street and in jail (T) is rising with it because police effort is not yet at a great enough intensity to arrest many addicts. The system structures of greatest importance during the first one hundred months are the positive feedback loops that create the growth of addict and user populations due to the growth of the drug culture, exposure to addicts, and increasing availability of hard drugs. During this period, community problem definition (U) remains very low because there has 868
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not yet been a police response that could produce frustration, nor have there been enough arrests to make it probable that some of those arrested will be familiar to a large segment of the community. The low value of crime (C) reflects the relatively small addict population and the relatively high early socioeconomic level of the area. When socioeconomic level is high, it is assumed that addicts will be able to get a lot of money they need from their families and would have to commit a small number of crimes per addict. Because there is not a large amount of crime, not much migration takes place and socioeconomic level (L) remains near its initial value. Total program cost ($) remains small due to the small initial number of police, the only program element operating during this simulation run. About one hundred months after the beginning of the run, another important positive feedback loop comes into play. Crime becomes high enough to begin to cause out-migration and socioeconomic level starts to drop. As it falls, the futility-despair level associated with lower levels of income begins to increase and with it grows the potential number of addicts. This potential is eventually converted to a larger addict populatiorl that commits more crime causing more migration, and a further drop in socioeconomic level. Crime begins to grow more rapidly because of this and because crime per addict is greater at lower socioeconomic levels due to the unavailability of family funds. Figure 5 amply illustrates the system structure underlying this behavior. The more rapid growth of the addict population is enabled by the excess inventories of hard drugs in the community created in response to the increased attractiveness of pushing. Here, more rapid growth of the addict population makes pushing more attractive which bring more drugs into the community and enables even more rapid growth. Another new mode of behavior arises at 170 months due to the action of the negative feedback loop embodying the police response. The police effort begins to grow in reaction to the rapidly increasing crime rate. This is reflected in the rapidly rising total program cost. It is also reflected in the rising community attitude that is produced by growing frustration with the results of the police efforts and increasing number of arrests relevant to community members. The number of addicts on the street reaches a plateau because, for a while, the police are able to make arrests at a rate equal to the rate at which new people become addicts. This, however, only amounts to transferring a growing part of the problem to jail as reflected in the total addict population in jail and on the street which continues to grow until 230 months. Growth of the total addict population peaks at that point, because the police effort has also decreased the drug supply. People who might potentially have become addicts lack the drug availability to do so and some addicts already in the area migrate to areas with more drugs and fewer police. As hard drug availability is reduced, the local price of drugs is driven up, forcing addicts to commit more crime to support their increasingly expensive habits. Near the end of the run, from month 250 onward, addicts on the street and total addicts both begin to grow again. This marks the inability of police effort to deal ultimately with the problem. Here, the positive feedback loops producing the growth of the problem regain dominance and overpower even a very strong police effort. Crime increases with the number of addicts and the community problem definition shifts more toward a
Figure 6-Base Computer Simulation Results: Police Used as Only Community Response 0~~~4
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