What Caused the Crime Decline?

Crime across the United States has steadily declined over the last two decades. Today, the crime rate is about half of what it was at its height in 1991. What was once seen as a plague, especially in urban areas, is now at least manageable in most places. Rarely has there been such a rapid change in mass behavior. This observation begs two central questions: Why has crime fallen? And to what degree is incarceration, or other criminal justice policy, responsible? Social scientists and policy experts have searched for answers. Various explanations have been offered: expanded police forces, an aging population, employment rates, and even legalized abortion. Most likely, there is no one cause for such widespread, dramatic change. Many factors are responsible.This report isolates two criminal justice policies -- incarceration and one policing approach -- and provides new findings on their effects on crime reduction using a regression analysis. This report issues three central findings, which are summarized: Increased incarceration at today's levels has a negligible crime control benefit:One policing approach that helps police gather data used to identify crime patterns and target resources, a technique called CompStat, played a role in bringing down crime in cities:Certain social, economic, and environmental factors also played a role in the crime drop

Gain curves in depletable food patches: A test of five models with European starlings

A forager's gain curve, the cumulative number of prey harvested from a patch as a function of time spent in the patch, influences optimal patch departure rules and interpretations of patch use data. We describe models of five different search strategies that yield different gain curves. Hence they would influence a forager's decision for patch departure differently and, consequently, how researchers should interpret patch residence times and giving-up densities. However, the models are virtually impossible to separate based on data of the gain curves per se. Therefore, we develop a series of diagnostic tests that can be used to discriminate among models. These tests consider how the instantaneous harvest rate within patches depends on initial (IPD) and current prey density (CPD) and search time. We applied these tests to data collected from European starlings (Sturnus vulgaris) foraging in experimental food patches of known initial prey density. The starlings' harvest rate increased with CPD, an indication of diminishing returns. However, a given CPD yielded a lower instantaneous intake rate the higher the IPD. Thus, the two models most commonly assumed in foraging studies, systematic and random search, can be unequivocally rejected. Instead, we found support for a new model, negative stirring, in which the starlings spoil their own future foraging returns by aggregating the remaining prey items as they search

Is Google the next Microsoft? Competition, Welfare and Regulation in Internet Search

Internet search (or perhaps more accurately `web-search') has grown exponentially over the last decade at an even more rapid rate than the Internet itself. Starting from nothing in the 1990s, today search is a multi-billion dollar business. Search engine providers such as Google and Yahoo! have become household names, and the use of a search engine, like use of the Web, is now a part of everyday life. The rapid growth of online search and its growing centrality to the ecology of the Internet raise a variety of questions for economists to answer. Why is the search engine market so concentrated and will it evolve towards monopoly? What are the implications of this concentration for different `participants' (consumers, search engines, advertisers)? Does the fact that search engines act as `information gatekeepers', determining, in effect, what can be found on the web, mean that search deserves particularly close attention from policy-makers? This paper supplies empirical and theoretical material with which to examine many of these questions. In particular, we (a) show that the already large levels of concentration are likely to continue (b) identify the consequences, negative and positive, of this outcome (c) discuss the possible regulatory interventions that policy-makers could utilize to address these

Through the Looking-Glass, and What OLS Found There: On Growth, Foreign Aid, and Reverse Causality

The cross-country literature on foreign aid effectiveness has relied on the use of instruments to distinguish causality from mere correlation. This paper uses simple non-instrumental techniques in the spirit of Granger to demonstrate that the main aid-growth connection is a negative causal relationship from growth to aid—-aid, that is, as a fraction of recipient GDP. Coarsely, when GDP goes up, aid/GDP goes down. The endogeneity of aid, long suspected, is real. Less understood is that adding certain common controls to regressions puts this relationship through the looking glass, flipping both its sign and apparent direction: aid seems to cause growth. Ideally, instrumentation expunges the endogeneity shown here. In practice, estimates of aid’s impact have run into problems. Autocorrelation in the errors is widespread, and can render endogenous lagged variables used as regressors or instruments. The pitfalls of “difference” and “system” include invalidity and proliferation of instruments. Multicollinearity in term pairs of interest, such as aid and aid2 or “project” and “program” aid, can amplify endogeneity bias. The combination of specification problems and widespread fragility (shown in earlier work) leads to pessimism about the ability of cross-country econometrics to demonstrate aid effectiveness. This does not rule an average positive effect, nor does it contradict the fact that aid has saved millions of lives, but it does suggest that the average effect on economic growth is too small to be detected statistically.foreign aid, economic growth

Wage Inequality in East-Central Europe

The substantial rise of wage inequality in Central and Eastern Europe has attracted the attention of sociologists, concerned with social equity, and economists for whom it indicated the growing differentiation and restructuring of relative prices on the labour market. This research wanted to study wage inequalities from the second point of view by analyzing relative wages during the transition period in Hungary and Romania. In this paper we would like to discuss the policy relevance of the research, summarize the main empirical findings and draw conclusions for policy.