and Zurich. Charles Wang has provided excellent research assistance. The views expressed herein are those of the authors and do not necessarily reflect the views of the National Bureau of Economic Research. NBER working papers are circulated for discussion and comment purposes. They have not been peerreviewed or been subject to the review by the NBER Board of Directors that accompanies official NBER publications.

No abstract

In this paper we study the causal impact of police on crime by looking at what happened to crime before and after the terror attacks that hit central London in July 2005. The attacks resulted in a large deployment of police officers to central London boroughs as compared to outer London -in fact, police deployment in central London increased by over 30 percent in the six weeks following the July 7 bombings. During this time crime fell significantly in central relative to outer London. Study of the timing of the crime reductions and their magnitude, the types of crime which were more likely to be affected and a series of robustness tests looking at possible biases all make us confident that our research approach identifies a causal impact of police on crime. Implementing an instrumental variable approach shows an elasticity of crime with respect to police of approximately -0.3, so that a 10 percent increase in police activity reduces crime by around 3 percent.

Although there is a large literature on the economic effects of minimum wages on labour market outcomes (especially employment), there is hardly any evidence on their impact on firm performance. This is surprising: minimum wages appear to have a significant impact on wages, but only a limited impact on jobs, so it is natural to imagine there must be a stronger impact on other aspects of firm behaviour. In this paper we consider the impact of minimum wages on firm profitability by exploiting the introduction of a minimum wage to the UK labour market in 1999. We use pre-policy information on the distribution of wages to construct treatment and comparison groups and implement a difference in differences approach. We show evidence that firm profitability was significantly reduced (and wages significantly raised) by the minimum wage introduction. This emerges from separate analyses of two distinct types of firm level panel data (one on firms in a very low wage sector, UK residential care homes, and a second on firms across all sectors). Interestingly, we find no evidence that the profitability reductions resulted in increases in firm exit, so our findings may be consistent with redistribution of quasi-rents towards low wage employees.

This article offers a guided tour to some of the main aspects of ICTs and productivity. It discusses a neoclassical theoretical framework that has been extensively used (either explicitly or implicitly) by most of the studies we survey. It also considers extensions to these theoretical approaches. It details some of the econometric issues involved in estimating the productivity of ICT. This requires some consideration of the estimation of production functions, an area where there has been considerable econometric advance in recent years. It also discusses issues relating to the data, both ideal and actual. Finally, it discusses the results of the empirical studies covering both growth accounting and econometric approaches at the industry and firm level.

Washington's `revolving door' -the movement from government service into the lobbying industry-is regarded as a major concern for policy-making. We study how ex-government staffers benefit from the personal connections acquired during their public service. Lobbyists with experience in the office of a US Senator suffer a 24% drop in generated revenue when that Senator leaves office. The effect is immediate, discontinuous around the exit period and long-lasting. Consistent with the notion that lobbyists sell access to powerful politicians, the drop in revenue is increasing in the seniority of and committee assignments power held by the exiting politician.

We study how ex-government officials benefit from the personal connections acquired during public service. Lobbyists with experience in the office of a US Senator suffer a 24% drop in generated revenue when that Senator leaves office. The effect is immediate, discontinuous around the exit period, and long-lasting. Consistent with the notion that lobbyists sell access to powerful politicians, the drop in revenue is increasing in the committee assignments power held by the exiting politician.Keywords: Lobbying, Revolving Door, US Congress, Political Connections, Political Elites.JEL Classification: H11, J24, J45. * We thank Nick Bloom, Andy Eggers, Steve Machin, Ignacio Palacios-Huerta, Yona Rubinstein, Ken Shepsle and James Snyder for insightful comments. We also thank participants at various conferences and seminars where we presented various versions of this work. We are grateful to the Centre for Responsive Politics, Columbia Books and LegiStorm for answering our questions regarding the data used in this paper. The Center for Economic Performance provided generous funding. We thank Johannes Schmieder for sharing STATA code with us. Victoria Loidl, Vithal Mittal and Jagveer Singh Kang provided excellent research assistance. All errors remain our own.

Although there is a large literature on the economic effects of minimum wages on labour market outcomes (especially employment), there is hardly any evidence on their impact on firm performance. This is surprising: minimum wages appear to have a significant impact on wages, but only a limited impact on jobs, so it is natural to imagine there must be a stronger impact on other aspects of firm behaviour. In this paper we consider the impact of minimum wages on firm profitability by exploiting the introduction of a minimum wage to the UK labour market in 1999. We use pre-policy information on the distribution of wages to construct treatment and comparison groups and implement a difference in differences approach. We show evidence that firm profitability was significantly reduced (and wages significantly raised) by the minimum wage introduction. This emerges from separate analyses of two distinct types of firm level panel data (one on firms in a very low wage sector, UK residential care homes, and a second on firms across all sectors). Interestingly, we find no evidence that the profitability reductions resulted in increases in firm exit, so our findings may be consistent with redistribution of quasi-rents towards low wage employees.