Criminal Justice M01dels: an Overview

If you have issues viewing or accessing this file contact us at NCJRS.gov. LOAN DOCUMENT RETURN TO: NCJRS P. O. BOX 24036 S. W. POST OFFICE WASHINGTON, D.C. 20024 CRIMINAL JUSTICE M01DELS: AN OVERVIEW NATIONAL INSTITUTE OF LAW ENFORCEMENT AND CRIMINAL JUSTICE II LAW ENFORCEMENT ASSISTANCE ADMINISTRATION ~ ~ UNITED STATES DEPARTMENT OF JUSTICE Ii I JME ~ETURN TO: , NCJRS P. O. BOX 24036 S. W. POST OFFICE WASHINGTON, D.C. 20024 CRIMINAL JUSTICE MODELS: AN OVERVIEW By J. Chaiken D. Jaquette NCJRS T. Crabill M. Lawless L. Holliday E.. Quade This project was supported by Grant Number 7S-NI-99-00l2 awarded to the· Rand Corporation by the National Institute of Law Enforcement and Criminal Justice, Law Enforcement Assistance Administration, U. S. Department of Justice, under the Omnibus Crirne Control and Safe Streets Act of 1968, as amended. Points of view or opinions stated in this document are those of the authors and do not neceSsar ily represent the official position or policies of the U. S. Departn'lent o[ Justice. APRIL 1976 National Institute of Law Enforcement and Criminal Justice Law Enforcement Assistance Administration U. S. Department of Justice J "t. ~~~:: ~' :. ,:r/r~ -.-"/:: t ,4'~ f , .. t li'!; ~~; ~~~ tJ;:~C!(}\ ~~J ~ t~t1r~~; ..:'i·:~~~~:/t,;i NATIONAL INSTITUTE OF LAW ENFORCEMENT AND CRIMINAL JUSTICE Gerald M. C~plan, Director FOREWORD Computer simulation models are widely recognized as valuable tools for plan LAW ENFORCEMENT ASSISTANCE ning and management. An effective model provides added insights by mathematical ADMINISTRATION ly projecting the consequences of alternative solutions to exceedingly complex prob lems. Originally designed for strategic military use, simulation models have since Richard W. Velde, Administralor gained acceptance throughout the public sector. Criminal justice agencies have been among the last to adopt computer models to the planning and decisionmaking Henry F. McQuade, Deputy Adminislrator process-in part, because it is only recently that the criminal justice system has Pau I K. W'Olrne I i I Deputy Administrator been treated as a system, rather than a series of unrelated parts. This study searches out examples of the best existing criminal justice simula tions, describes their characteristics, and discusses their value for criminal justice agencies. It is an excellent resource for criminal justice administrators considering the use of a simulation model. Gerald M. Caplan Director National Institute of Law Enforcement and Criminal Justice l?ol' sllle b)· the Supel'intendent of Documents, U.S, GOVClt'nmenl Printing Ofllcc Washington, D,C, 20402 • Price $2,50 Stock No. 027-000-00420-6 PREFACE 'This review of criminal justice models was funded by the National Institute of Law Enforcement and Criminal Justice of the Law Enforce.ment Assistance Ad ministration under grant 75-NI-99-0012. The report is written primarily for the guidance of • Criminal justice planners who wish to locate a suitable model for a particu lar application • Criminal justice funding agency personnel • Model builders The summary of this report is written in nontechnical language and is intended as an executive summary for administrators of criminal justice planning- agencies. The body of the report contains some technical details, but these are explained in either the text or the glossary. The authors have attempted to be impartial in reviewing individual models. However, it must be admit.ted that complete impartiality was impossible, because some of the models were developed by one ofthe authors or by coll©agues at The New York City-Rand Institute. These models may have been treated more positively or more negatively than the others, due to greater familiarity with their design, docu mentation, or history of implementation. The reader must understand that this is a limitation of any review article where the authors have some past association with work in the field. The contributions of each of the authors to this report are as follows: Leo Holliday, project leadership and Chapters 5 and 6; Edward Quade, Chapter 2; David Jaquette, Chapter 3; Jan Chaiken and Thomas Crabill, Chapter 4; Michael Lawless, Chapter 7. The remaining parts of the report were written by Jan Chaiken based on materials drafted by all the authors. iii ".1ooioiOio., ..'. f \ SUMMARY l 'fhe term "model" refers to a device or procedure for providing insight into the consequences of a decision. For this study we reviewed models related to the crimi nal justice system that (a) operate on a computer and (b) are intended to assist decisionmaking by criminal justice agencies. This study located 46 such models in 1974. Based on the adequacy of documentation and the availability of the computer programs to criminal justice agencies that might want to use them in the future, 20 of these 46 models were selected for detailed description in the text. 2 These descrip tions are intended to be adequate for criminal justice planners and policymakers to determine whether an appropriate model already exists for handling a particular problem, and, if so, which one would best meet their needs. In addition to describing the models, this study reviewed the circumstances under which criminal justice models are or are not implemented by operating and planning agencies. In general, models have failed to achieve the level of use for policy decisions that was intended by the model builders and those who funded them. Our findings concerning the causes of implementation successes and failures indi cate how federal research administrators might improve the quality and usefulness of models in the future. APPRAISING MODELS While, in principle, models can be designed to assist policymakers in nearly any kind of decision, in practice no one would take the effort to use a model unless the decision presents difficulties such as one of the following: • So many alternatives are available that it is not practical to consider each one before selecting the best. • The consequences of each alternative are too complex to be anticipated with assurance. • Numerous tedious calculations must be performed to evaluate each alter native. • The decision must be performed rapidly following specified rules (e.g., selecting a particular patrol car to dispatch to a reported crime). In such situations a model can provide vital information that otherwise would not be available for making the decision. In addition, models produce clear documenta tion of the decision process that can help persuade others of the correctness of the policymaker's position. No models can tell a policy maker exactly what decision he should make in a given situation. Instead, models must be used with common sense, good judgment, I References to the literature describing the models and studies mentioned in this summary are given in the body of the report. See glosstlry for definitions of unfamiliar terms. 2 The actual number of illodels discussed in the text is larger, because some submodels are reviewed separately, and some unselected models are described in an histori(!al context. v vii vi TYPES OF MODELS and an understanding of political and budgetary constraints to make decisions. Some models, descriptive in nature, do not even pretend to suggest any policy recom The basic types of models of interest in the criminal justice field are as Collows: mendation; they simply provide a tool for anticipating the consequences of policy • Analytic models. These determine an outr:ome or solution from mathemati changes invented by the user. Other models prescribe a "best" solution to a specified cal analysis, such as solving a set of equations. Generally, many Ceatures problem, but even here the user often has a choice of how the term "bes~' is to be of the system to be studied are ignored or simplified in an an.alytlc I:1?del, defined, and he always~las to use his own judgment in weighing performance char but the results may nonetheless be accurate enough fol' polIcy decIsIons. acteristics not encompassed by the model builder's definition of t!best." One type of analytic model is an opti.mization model; this tells how to If it appears that a model could potentially be helpful, the policymaker must obtain the loweat or highest possible value of some performance measure then know how to appraise particular models to determine whether they are suit (for example, how to schedule a fixed number of conrt cases in a week so able. Several factors must be considered. Most important is the match between the as to handle them with the lowest possible cost). model ancl the policy issue to be addressed. A very accurate model that answers a question orno interest to the agency would not be of any value. Next is the time until • ComplLter simulations. These imitate the operations of a system so as to completion oCthe mod~l. Ifa decision must be made before the model can be installed produce the same statistical behavior as found in the real ,:orld: .For exam and appropriate data can be collected, then the model will not be useful. ple, a simulation model could follow a large number of Imagll1ary court Technical quality of a model is oO;en difficult for a policymaker to judge, but cases, keeping track of the dates of their appear~nces, the outcome ofe~ch evidence that verification and validation ofthe model have been (or will be) conduct· case, and so forth. The output of the simulatIon model would descnbe ed should serve as adequate assurances of quality. Verification refers to checking statistical properties of all the imaginary cases, for example the average that th6 model does what the model builder intended it should do. This is accom length of time from arraignment to final disposition fur burglary deCen plished by using test data for which the answer ie known or by comparing one model dants not released on bail.

Load more