The Difference Between Short and Long Run Effects of Police Outlays on Crime: Policing Deters Criminals Initially, But Later They May 'Learn by Doing'

Abstract . In the long run a positive relationship of police expenditurescrime is derived in models which explain criminal behavior In the short run, however, the statistical results point to the possible deterring effect of police expenditures. A theoretical model is constructed to explain the statistical difference of the short and long run effect of police outlays on crime. As police expenditures increase, crime level diminishes. As time elapses, criminals may adjust to the new level of police effort, improve their performance and at the same level of outlays, increase their criminal activities. This phenomenon could be termed “Criminals’Learning by Doing”. It could explain why, over the long run, the level of crime is positively associated with police expenditures. The empirical analysis examines pooled cross sectional time series of 47 states over the period 1970 to 1980—a total of 517 cases.     

The deterrence hypothesis revisited

This study explores the causes of crime and the differences in deterrent effects of policing on crimes among rural, suburban, and urban communities. We hypothesize that certain numbers of all crimes are unaffected by policing due to their high net return; policing deters only marginal crimes. That is, unlike other research efforts, we recognize that there is a level of crime indigenous to a given type of community about which little can be done, although a particular community can affect deviations from this level. By introducing this ‘natural rate' of crime we are able to empirically reveal the deterrence effect of police expenditures upon all types of property crimes except robberies. The study analyzes 230 communities in a system of six simultaneous equations, using police, crime, and other socio-economic variables. The model can be used by state and regional policy-makers to more effectively allocate resources to the different types of communities under their jurisdiction and among the various police functions designed to deter specific types of crime.     

Crime Rates,Clearance Rates and Enforcement Effort: The Case of Houston,Texas*

Abstract . Two time series relationships with respect to police and criminal activities are analyzed. These relationships are: 1. That between police input and police output where the latter was measured by arrest and convictions rates and the former by expenditures and number of officers and, 2. The hypothetical one between the probability of arrest (the clearance ratio; i.e., the proportion of reported crimes for which arrests were made) and crime rates. Theoretically, an increase in expenditures for police effort would cause an increase in the clearance rate and a concomitant reduction in the crime rate. The results of this study showed little or no response in clearance and crime rates to small changes in police expenditures. However, there was evidence that large changes in police effort did produce some response in both clearance and crime rates. The implication of these findings was that the marginal product of police input was small.     

Stability of a crime level equilibrium

We consider crime level in an economic market with a supply of potential criminals. These criminals differ in their opportunity cost for committing crime, reflecting differences in the value of foregone opportunities such as performing productive labor. The realized demand is influenced by the expected value for crime, which depends on several socio-economic variables including wealth, police enforcement, and police arrest ability. After determining the equilibria level suggested by our approach, we propose a dynamic setup and study the stability of this system. Two critical enforcement levels are determined. Exceeding the lower enforcement threshold will push crime to stabilize (converge) to an equilibrium level. Correspondingly, exceeding the higher enforcement threshold will collapse the crime market to zero.     

The Economics of the Criminal Behavior of Young Adults

A bstract This study uses a combination of individual-level and county-level data to estimate an economic model of crime for young adults similar to that used by Becker (1968) and Trumbull (1989). In order to estimate a model of crime in which both individual-level and county-level data are used, it is necessary to take account of the bias introduced by using aggregate-level data in conjunction with individual-level data. In order to eliminate this bias, a technique derived by Moulton (1990) is employed. Results from a logit regression model indicate that race, sex. and peer pressure have statistically significant effects on the probability that a young adult will commit a crime. Results also suggest that police presence, as measured by county-level per capita police expenditures, does not deter young adults from committing crimes.     

Predicting the geo-temporal variations of crime and disorder

Traditional police boundaries—precincts, patrol districts, etc.—often fail to reflect the true distribution of criminal activity and thus do little to assist in the optimal allocation of police resources. This paper introduces methods for crime incident forecasting by focusing upon geographical areas of concern that transcend traditional policing boundaries. The computerised procedure utilises a geographical crime incidence-scanning algorithm to identify clusters with relatively high levels of crime (hot spots). These clusters provide sufficient data for training artificial neural networks (ANNs) capable of modelling trends within them. The approach to ANN specification and estimation is enhanced by application of a novel and noteworthy approach, the Gamma test (GT).     

The deterrent impact of police: An examination of a locally provided public service

This paper develops and empirically tests a model of crime deterrence in an urban area. There are two important departures from past efforts to study the impact of criminal sanctions. The first is that the provision of sanctions from the local public sector is modeled; this is accomplished by specifying the distributional goals of local government and by specifying the production of safety. The second departure is that actual crime and reported crime are differentiated theoretically and in the empirical work. An empirical test of the model, using a unique neighborhood data set, shows that police deter crime significantly; however, this deterrent impact cannot be demonstrated without the distinction between actual and reported crime.     

On minimizing the welfare cost of fiscal policy: evidence from South Asia

This study evaluates whether India, Pakistan, and Sri Lanka minimized the welfare cost of their fiscal policies? For this purpose it tests tax smoothing hypothesis and finds that there is a weak tax smoothing in Pakistan and Sri Lanka whilst fiscal policy in India has not been conducted in an optimal fashion in accordance with the predictions of the hypothesis. The difference in results is due to difference in budget deficits as the deficits of Pakistan and Sri Lanka are higher as compare to India so they are careful to reduce volatility in budget deficits by trying to keep close correspondence between taxes and expenditures while India, with comparatively less deficit, was more careful regarding its debt. Therefore, to minimize the cost a close correspondence between permanent expenditure and taxes are required. In this context the best policy option would be an initiation of prompt action program of tax base expansions and expenditure rationalization.     

An analytic approach to the study of gun control policies

This paper explores the theoretic and policy implications of the assumption that the objective of gun ownership is to enhance the security of gun owners and their associates. Security is defined as the probability of not being victimized in a criminal assault and not suffering accidental injury or death in a gun-related incident. An elementary mathematical model is constructed and analyzed. This model and controversial data currently available lead to the conclusion that the percentage of the population owning guns should be larger than now it is. This result does not imply that gun ownership should be made more accessible. Gun ownership may be one possible way to reduce crime. Other ways to achieve this objective are better police control, education, socio-economic justice, etc. The possibility that these alternatives are more effective crime deterrents is not explored in this paper, nor in the studies that provided the data. This evaluation is needed before deciding whether increased gun ownership is the policy that should be adopted in order to reduce crime.     

Short-term forecasting of crime

The major question investigated is whether it is possible to accurately forecast selected crimes 1 month ahead in small areas, such as police precincts. In a case study of Pittsburgh, PA, we contrast the forecast accuracy of univariate time series models with naïve methods commonly used by police. A major result, expected for the small-scale data of this problem, is that average crime count by precinct is the major determinant of forecast accuracy. A fixed-effects regression model of absolute percent forecast error shows that such counts need to be on the order of 30 or more to achieve accuracy of 20% absolute forecast error or less. A second major result is that practically any model-based forecasting approach is vastly more accurate than current police practices. Holt exponential smoothing with monthly seasonality estimated using city-wide data is the most accurate forecast model for precinct-level crime series.     

Private security and the public safety

The demand for private protection and the effect of such protective measures on the level of crime are examined. Private protection may reduce a household's expected victimization rate either by deterring some crime or by diverting crime to other households. The greater the relative importance of the latter effect, the more likely a community is to “tip” in the direction of deserting the streets at night and taking other precautions. Data on crime and protection are analyzed, but they are inadequate for a full estimation of the model. The paper concludes with a normative analysis of protection and implications for social policy.     

POLICING FOR THE PEOPLE

Increased spending on law and order over the last decade has not been matched by reductions in crime. The government's claim to have reduced crime does not reflect reality and the public know this. The way to rebuild public confidence and tackle crime is to put more police officers back on the streets. This article argues that in order to do this, four key reforms of the police are needed: a reduction in bureaucracy and central intervention; greater accountability to local communities; more co-operation between forces; and the modernisation of working practices.     

基于成本差异的最佳贸易与产业政策选择

本文讨论了存在成本差异的第三国市场模型的最佳贸易与产业政策选择问题，讨论了社会成本和私人成本、本国和外国成本差异情况下的Cournot竞争和Bertrand竞争的情况。本文发现，在Cournot竞争下，政府首先行动时，当政府基金影子价格低于4／3时，政府对出口进行补贴，并且本国越有成本优势，补贴越高，补贴的利润转移效应越大；当政府基金影子价格高于4／3时，政府对出口征收出口税，且本国越有成本优势，征税越多。在Bertrand竞争下，当政府先行动时，对出口征收出口税；当政府后行动时，对出口进行补贴。当本国企业具有劣势时，事后补贴是最佳政蓑。     

The Interdependence of Municipal and County Police Forces:

A bstract — In our politically fragmented urban areas, sheriff's police services, like all municipal services, are distributed free of any direct charge. This study attempts to determine the optimal quantities of county police activity each political district should receive as well as their matching tax bills. The outcome of the analysis is pronouncedly influenced by the peculiar nature of externalities that occur in the provision of urban law enforcement services. Achievement of optimality conditions indicates an inverse relationship between sheriff's per capita expenditures and per capita tax base values of the participating political units.     

Larceny

A dynamic general equilibrium model of larceny - or property crime - is presented in which both economic conditions and government policies affect the commission calculus. The model provides a behavioral framework that is used to estimate the effects of government policies on the commission of larceny. Calibrating the model using data from cities in Los Angeles County, the impact of a number of government policies and of economic development on larceny are quantified. The simulations show that longer prison sentences and higher conviction rates for criminals are the most effective methods to reduce larceny; subsidizing leisure activities, increasing police expenditures and income transfers have little effect on larceny. Using a game-theoretic optimality criterion, all the policies examined are currently overfunded.     

A mutual insurance diffusion stochastic control problem

This paper determines the optimal loading factor policy of a mutual insurance firm. Insurance is viewed as a collective process of N persons paying fixed (or variable, contingent) premiums and seeking protection against claims. Risk reduction for each person is then exercised through a distribution of risk by aggregating individual risks and by accumulating cash (net of operating expenses) to meet possible contingent claims. By assuming an approximate claims diffusion process, stochastic control problems for selecting the optimum loading factor policies are stated and resolved analytically. In particular, the implicit cost of bankruptcy is computed and an optimum variable-feedback loading policy is established.     

The effect of spatiotemporal resolution on predictive policing model performance

Being able to anticipate crime such that new crime events can be dealt with effectively or prevented entirely, leads police forces worldwide to look at applying predictive policing, which provides predictions of times and places at risk for crime, such that proactive preventative measures can be taken. Ideally, predictive policing models predict crime at a high spatio-temporal level, while also providing optimal prediction performance. The main objective of this paper is therefore to evaluate the impact of varying grid resolution, temporal resolution and historical time frame on prediction performance. To investigate this, we analyse home burglary data from a large city in Belgium and predict new crime events using a range of parameter values, comparing the resulting prediction performances. Given the potential prediction performance costs associated with prediction at a high spatio-temporal resolution, consideration should be given to balance practical requirements with performance requirements.     

不确定条件下环境政策的时机选择

本文建立了一个连续时间模型，用于分析不确定条件下环境政策的时机选择。模型结果显示，环境政策的采用有两种不可逆性，而且它们在相反的方向上起作用：第一，旨在降低生态危害的政策对社会施加了沉淀成本。它产生立即采用这一政策而不是等待有关生态影响及其经济后果的更多信息的机会成本，这种机会成本使等待而不是现在就采纳政策更可取；第二，环境危害可能部分或完全不可逆。这就意味着立即采用一项政策而不是等待具有沉没收益，即负的机会成本。这种负的机会成本偏离了政策采用中传统的成本一收益分析。因此，现在立即采用一项政策可能是更合适的，即使传统的分析宣称它是不经济的。文章表明，不确定性对环境政策的时机选择有着重要的影响。     

When is it efficient to treat juvenile offenders more leniently than adult offenders?

This paper provides a rationale for two characteristics of juvenile justice systems. First, juvenile justice systems tend to be more lenient in terms of both incarceration rates and time incarcerated. Second, higher expenditures are made to incarcerate a juvenile offender than an adult prisoner. It does this by examining the effect juvenile incarceration has on human capital acquisition and in turn, later incentives to commit crime as adults. In the process, it also offers an explanation of the empirical finding that individuals arrested as juveniles are more likely to be arrested as adults.     

Optimal Processes Management for Over-Adjusted Process with Dependent Steps on Bank Industry

Process management is important for a company. An over-adjusted process may increase process quality variability, ultimately affecting the quality and cost of service or products. A two special-cause economic over-adjustment model is developed for controlling the service quality variation of the two-step process on a bank industry. The objective is to determine the optimal management policy for the two-step process, which minimizes the service quality variation and total quality control cost. A Markov chain approach is extended to derive the economi c adjustment model of the process, and the optimal management policy is obtained from optimization techniques. Application of the two special-cause over-adjusted model and the optimal management policy on the process management of a bank industry is demonstrated through an example.