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Showing papers by "National Bureau of Economic Research published in 2006"


Journal ArticleDOI
TL;DR: In this article, the authors construct estimates of external assets and liabilities for 145 countries for the period 1970-2004, focusing on trends in net and gross external positions, and the composition of international portfolios.
Abstract: We construct estimates of external assets and liabilities for 145 countries for the period 1970-2004. We describe our estimation methods and present key features of the data at the country and the global level. We focus on trends in net and gross external positions, and the composition of international portfolios, distinguishing between foreign direct investment, portfolio equity investment, official reserves, and external debt. We document the increasing importance of equity financing and the improvement in the external position for emerging markets, and the differing pace of financial integration between advanced and developing economies. We also show the existence of a global discrepancy between estimated foreign assets and liabilities, and identify the asset categories that account for this discrepancy.

2,536 citations


Journal ArticleDOI
TL;DR: This paper introduced culturally-based explanations into economics that can be tested and may substantially enrich our understanding of economic phenomena, and summarized this approach and its achievements so far, and outlines directions for future research.
Abstract: Until recently, economists have been reluctant to rely on culture as a possible determinant of economic phenomena. Much of this reluctance stems from the very notion of culture: it is so broad and the channels through which it can enter the economic discourse so ubiquitous (and vague) that it is difficult to design testable, refutable hypotheses. In recent years, however, better techniques and more data have made it possible to identify systematic differences in people's preferences and beliefs and to relate them to various measures of cultural legacy. These developments suggest an approach to introducing culturally-based explanations into economics that can be tested and may substantially enrich our understanding of economic phenomena. This paper summarizes this approach and its achievements so far, and outlines directions for future research.

2,172 citations


Journal ArticleDOI
TL;DR: In this article, the authors argue that the term "ecosystem services" is too ad hoc to be of practical use in welfare accounting and propose a definition, rooted in economic principles, of ecosystem service units.
Abstract: This paper advocates consistently defined units of account to measure the contributions of nature to human welfare. We argue that such units have to date not been defined by environmental accounting advocates and that the term "ecosystem services" is too ad hoc to be of practical use in welfare accounting. We propose a definition, rooted in economic principles, of ecosystem service units. A goal of these units is comparability with the definition of conventional goods and services found in GDP and the other national accounts. We illustrate our definition of ecological units of account with concrete examples. We also argue that these same units of account provide an architecture for environmental performance measurement by governments, conservancies, and environmental markets.

1,758 citations


Journal ArticleDOI
TL;DR: This article showed that the import of new product varieties has contributed to national welfare gains in the United States over the last three decades (1972-2001) by increasing the number of imported product varieties by a factor of four.
Abstract: Since the seminal work of Krugman (1979), product variety has played a central role in models of trade and growth. In spite of the general use of love-of-variety models, there has been no systematic study of how the import of new varieties has contributed to national welfare gains in the United States. In this paper we show that the unmeasured growth in product variety from US imports has been an important source of gains from trade over the last three decades (1972-2001). Using extremely disaggregated data, we show that the number of imported product varieties has increased by a factor of four. We also estimate the elasticities of substitution for each available category at the same level of aggregation, and describe their behavior across time and SITC-5 industries. Using these estimates we develop an exact price index and find that the upward bias in the conventional import price index is approximately 1.2 percent per year – double the estimated impact due to hedonic adjustments on the CPI. The magnitude of this bias suggests that the welfare gains from variety growth in imports alone are 2.8 percent of GDP per year.

1,735 citations


Journal ArticleDOI
TL;DR: In this paper, the authors study the effect of market entry regulations on the creation of new limited-liability firms, the average size of entrants, and the growth of incumbent firms.

1,501 citations


Journal ArticleDOI
TL;DR: In this paper, the authors examine the different methods used in the literature and explain when the different standard errors yield the same (and correct) standard errors and when they diverge.
Abstract: In both corporate finance and asset pricing empirical work, researchers are often confronted with panel data. In these data sets, the residuals may be correlated across firms or across time, and OLS standard errors can be biased. Historically, the two literatures have used different solutions to this problem. Corporate finance has relied on clustered standard errors, while asset pricing has used the Fama-MacBeth procedure. This paper examines the different methods used in the literature and explains when the different methods yield the same (and correct) standard errors and when they diverge. The intent is to provide intuition as to why the different approaches sometimes give different answers and give researchers guidance for their use.

1,255 citations


Posted Content
TL;DR: The authors analyzes a marked change in the evolution of the U.S. wage structure over the past fifteen years: divergent trends in upper-tail and lower-tail (50/10) wage inequality, with employment polarizing into high-wage and low-wage jobs at the expense of middle-wage work.
Abstract: This paper analyzes a marked change in the evolution of the U.S. wage structure over the past fifteen years: divergent trends in upper-tail (90/50) and lower-tail (50/10) wage inequality. We document that wage inequality in the top half of distribution has displayed an unchecked and rather smooth secular rise for the last 25 years (since 1980). Wage inequality in the bottom half of the distribution also grew rapidly from 1979 to 1987, but it has ceased growing (and for some measures actually narrowed) since the late 1980s. Furthermore we find that occupational employment growth shifted from monotonically increasing in wages (education) in the 1980s to a pattern of more rapid growth in jobs at the top and bottom relative to the middles of the wage (education) distribution in the 1990s. We characterize these patterns as the %u201Cpolarization%u201D of the U.S. labor market, with employment polarizing into high-wage and low-wage jobs at the expense of middle-wage work. We show how a model of computerization in which computers most strongly complement the non-routine (abstract) cognitive tasks of high-wage jobs, directly substitute for the routine tasks found in many traditional middle-wage jobs, and may have little direct impact on non-routine manual tasks in relatively low-wage jobs can help explain the observed polarization of the U.S. labor market.

1,251 citations


ReportDOI
TL;DR: In this paper, a minimalist derivation of the gravity equation is used to identify three common errors in the literature, what they call the gold, silver and bronze medal errors, and estimates of the size of the biases taking the currency union trade effect as an example.
Abstract: This paper provides a minimalist derivation of the gravity equation and uses it to identify three common errors in the literature, what we call the gold, silver and bronze medal errors. The paper provides estimates of the size of the biases taking the currency union trade effect as an example. We generalize Anderson-Van Wincoop’s multilateral trade resistance factor (which only works with cross section data) to allow for panel data and then show that it can be dealt with using time-varying country dummies with omitted determinants of bilateral trade being dealt with by time-invariant pair dummies.

1,171 citations


Journal ArticleDOI
TL;DR: In this paper, the authors observed a highly significant relation between the decision to pay dividends and the earned/contributed capital mix, controlling for profitability, growth, firm size, total equity, cash balances, and dividend history, a relation that also holds for dividend initiations and omissions.

1,094 citations


Journal ArticleDOI
TL;DR: In this paper, the authors analyzed the link between corporate tax avoidance and the growth of high-powered incentives for managers and found that increases in incentive compensation tend to reduce the level of tax sheltering, in a manner consistent with a complementary relationship between diversion and sheltering.

1,086 citations


Journal ArticleDOI
30 Jun 2006-Science
TL;DR: It is argued that people exaggerate the contribution of income to happiness because they focus, in part, on conventional achievements when evaluating their life or the lives of others.
Abstract: The belief that high income is associated with good mood is widespread but mostly illusory. People with above-average income are relatively satisfied with their lives but are barely happier than others in moment-to-moment experience, tend to be more tense, and do not spend more time in particularly enjoyable activities. Moreover, the effect of income on life satisfaction seems to be transient. We argue that people exaggerate the contribution of income to happiness because they focus, in part, on conventional achievements when evaluating their life or the lives of others.

Posted Content
TL;DR: In this article, the authors investigate how and why the productivity of a worker varies as a function of her co-workers in a group production process, and find strong evidence of positive productivity spillovers from the introduction of highly productive personnel into a shift.
Abstract: We investigate how and why the productivity of a worker varies as a function of the productivity of her co-workers in a group production process. In theory, the introduction of a high productivity worker could lower the effort of incumbent workers because of free riding; or it could increase the effort of incumbent workers because of peer effects induced by social norms, social pressure, or learning. Using scanner level data, we measure high frequency, worker-level productivity of checkers for a large grocery chain. Because of the firm's scheduling policy, the timing of within-day changes in personnel is unsystematic, a feature for which we find consistent support in the data. We find strong evidence of positive productivity spillovers from the introduction of highly productive personnel into a shift. A 10% increase in average co-worker permanent productivity is associated with 1.7% increase in a worker's effort. Most of this peer effect arises from low productivity workers benefiting from the presence of high productivity workers. Therefore, the optimal mix of workers in a given shift is the one that maximizes skill diversity. In order to explain the mechanism that generates the peer effect, we examine whether effort depends on workers' ability to monitor one another due to their spatial arrangement, and whether effort is affected by the time workers have previously spent working together. We find that a given worker's effort is positively related to the presence and speed of workers who face him, but not the presence and speed of workers whom he faces (and do not face him). In addition, workers respond more to the presence of co-workers with whom they frequently overlap. These patterns indicate that these individuals are motivated by social pressure and mutual monitoring, and suggest that social preferences can play an important role in inducing effort, even when economic incentives are limited.

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a bank-based explanation for the decade-long Japanese slowdown following the asset price collapse in the early 1990s, and showed that zombie-dominated industries exhibit more depressed job creation and destruction, and lower productivity.
Abstract: In this paper, we propose a bank-based explanation for the decade-long Japanese slowdown following the asset price collapse in the early 1990s. We start with the well-known observation that most large Japanese banks were only able to comply with capital standards because regulators were lax in their inspections. To facilitate this forbearance the banks often engaged in sham loan restructurings that kept credit flowing to otherwise insolvent borrowers (that we call zombies). Thus, the normal competitive outcome whereby the zombies would shed workers and lose market share was thwarted. Our model highlights the restructuring implications of the zombie problem. The counterpart of the congestion created by the zombies is a reduction of the profits for healthy firms, which discourages their entry and investment. In this context, even solvent banks do not find good lending opportunities. We confirm our story's key predictions that zombie-dominated industries exhibit more depressed job creation and destruction, and lower productivity. We present firm-level regressions showing that the increase in zombies depressed the investment and employment growth of non-zombies and widened the productivity gap between zombies and non-zombies.

Journal ArticleDOI
TL;DR: In this paper, the authors construct a model of simultaneous change and persistence in institutions, where the main idea is that equilibrium economic institutions are a result of the exercise of de jure and de facto political power.
Abstract: We construct a model of simultaneous change and persistence in institutions. The model consists of landowning elites and workers, and the key economic decision concerns the form of economic institutions regulating the transaction of labor (e.g., competitive markets versus labor repression). The main idea is that equilibrium economic institutions are a result of the exercise of de jure and de facto political power. A change in political institutions, for example a move from nondemocracy to democracy, alters the distribution of de jure political power, but the elite can intensify their investments in de facto political power, such as lobbying or the use of paramilitary forces, to partially or fully offset their loss of de jure power. In the baseline model, equilibrium changes in political institutions have no effect on the (stochastic) equilibrium distribution of economic institutions, leading to a particular form of persistence in equilibrium institutions, which we refer to as invariance. When the model is enriched to allow for limits on the exercise of de facto power by the elite in democracy or for costs of changing economic institutions, the equilibrium takes the form of a Markov regime-switching process with state dependence. Finally, when we allow for the possibility that changing political institutions is more difficult than altering economic institutions, the model leads to a pattern of captured democracy, whereby a democratic regime may survive, but choose economic institutions favoring the elite. The main ideas featuring in the model are illustrated using historical examples from the U.S. South, Latin America and Liberia.

Journal ArticleDOI
TL;DR: In this article, an equally weighted index of monthly returns of commodity futures for the July 1959 through December 2004 period was constructed for the same return and Sharpe ratio as U.S. equities.
Abstract: For this study of the simple properties of commodity futures as an asset class, an equally weighted index of monthly returns of commodity futures was constructed for the July 1959 through December 2004 period. Fully collateralized commodity futures historically have offered the same return and Sharpe ratio as U.S. equities. Although the risk premium on commodity futures is essentially the same as that on equities for the study period, commodity futures returns are negatively correlated with equity returns and bond returns. The negative correlation is the result, primarily, of commodity futures' different behavior over a business cycle. Commodity futures are positively correlated with inflation, unexpected inflation, and changes in expected inflation.

Journal ArticleDOI
TL;DR: In this paper, the authors show that informational shrouding flourishes even in highly competitive markets, even in markets with costless advertising, and even when the shrouding generates allocational inefficiencies.
Abstract: Bayesian consumers infer that hidden add-on prices (e.g., the cost of ink for a printer) are likely to be high prices. If consumers are Bayesian, firms will not shroud information in equilibrium. However, shrouding may occur in an economy with some myopic (or unaware) consumers. Such shrouding creates an inefficiency, which firms may have an incentive to eliminate by educating their competitors' customers. However, if add-ons have close substitutes, a "curse of debiasing" arises, and firms will not be able to profitably debias consumers by unshrouding add-ons. In equilibrium, two kinds of exploitation coexist. Optimizing firms exploit myopic consumers through marketing schemes that shroud high-priced add-ons. In turn, sophisticated consumers exploit these marketing schemes. It is not possible to profitably drive away the business of sophisticates. It is also not possible to profitably lure either myopes or sophisticates to nonexploitative firms. We show that informational shrouding flourishes even in highly competitive markets, even in markets with costless advertising, and even when the shrouding generates allocational inefficiencies.

Posted ContentDOI
TL;DR: In this paper, the Blinder-Oaxaca decomposition technique is used to identify and quantify the separate contributions of group differences in measurable characteristics, such as education, experience, marital status, and geographical differences to racial and gender gaps in outcomes.
Abstract: The Blinder-Oaxaca decomposition technique is widely used to identify and quantify the separate contributions of group differences in measurable characteristics, such as education, experience, marital status, and geographical differences to racial and gender gaps in outcomes. The technique cannot be used directly, however, if the outcome is binary and the coefficients are from a logit or probit model. I describe a relatively simple method of performing a decomposition that uses estimates from a logit or probit model. Expanding on the original application of the technique in Fairlie (1999), I provide a more thorough discussion of how to apply the technique, an analysis of the sensitivity of the decomposition estimates to different parameters, and the calculation of standard errors.

Posted Content
TL;DR: This article used three longitudinal data sets of high school graduates in 1957, 1972, and 1992 to understand the narrowing of the gender gap in college and its reversal, finding that from 1972 to 1992 high school girls narrowed the gap with boys in math and science course taking and in achievement test scores.
Abstract: Women are currently the majority of U.S. college students and of those receiving a bachelor%u2019s degree, but were 39 percent of undergraduates in 1960. We use three longitudinal data sets of high school graduates in 1957, 1972, and 1992 to understand the narrowing of the gender gap in college and its reversal. From 1972 to 1992 high school girls narrowed the gap with boys in math and science course taking and in achievement test scores. These variables, which we term the proximate determinants, can account for 30 to 60 percent of the relative increase in women%u2019s college completion rate. Behind these changes were several others: the future work expectations of young women increased greatly between 1968 and 1979 and the age at first marriage for college graduate women rose by 2.5 years in the 1970s, allowing them to be more serious students. The reversal of the college gender gap, rather than just its elimination, was due in part to the persistence of behavioral and developmental differences between males and females.

Journal ArticleDOI
TL;DR: A review of the literature that has emerged from these efforts can be found in this paper, where the authors focus on the individual firm, studying its choices in response to its own characteristics, the nature of the industry in which it operates, and the opportunities afforded by foreign trade and investment.
Abstract: New developments in the world economy have triggered research designed to better understand the changes in trade and investment patterns, and the reorganization of production across national borders. Although traditional trade theory has much to offer in explaining parts of this puzzle, other parts required new approaches. Particularly acute has been the need to model alternative forms of involvement of business firms in foreign activities, because organizational change has been central in the transformation of the world economy. This paper reviews the literature that has emerged from these efforts. The theoretical refinements have focused on the individual firm, studying its choices in response to its own characteristics, the nature of the industry in which it operates, and the opportunities afforded by foreign trade and investment. Important among these choices are organizational features, such as sourcing strategies. But the theory has gone beyond the individual firm, studying the implications of firm behavior for the structure of industries. It provides new explanations for trade structure and patterns of FDI, both within and across industries, and has identified new sources of comparative advantage.

Journal ArticleDOI
TL;DR: In this article, a multi-dimensional empirical model was proposed to study how financial contracts respond to the legal and institutional environment, showing that loans with strong creditor protection have concentrated ownership, long maturity and low interest rates.
Abstract: Legal and institutional differences shape the ownership and terms of bank loans across the world. With strong creditor protection, we show that loans have concentrated ownership, long maturity and low interest rates. The impact of creditor rights on loans also depends on borrower characteristics such as the size and tangibility of assets. Foreign banks appear especially sensitive to the legal and institutional environment. Their ownership declines relative to domestic banks as creditor protection falls. Our multi-dimensional empirical model paints a more complete picture of how financial contracts respond to the legal and institutional environment than existing studies.

Journal ArticleDOI
TL;DR: In this article, the authors use five decades of time-use surveys to document trends in the allocation of time and find that a dramatic increase in leisure time lies behind the relatively stable number of market hours worked (per working-age adult) between 1965 and 2003.
Abstract: In this paper, we use five decades of time-use surveys to document trends in the allocation of time. We find that a dramatic increase in leisure time lies behind the relatively stable number of market hours worked (per working-age adult) between 1965 and 2003. Specifically, we show that leisure for men increased by 6-8 hours per week (driven by a decline in market work hours) and for women by 4-8 hours per week (driven by a decline in home production work hours). This increase in leisure corresponds to roughly an additional 5 to 10 weeks of vacation per year, assuming a 40-hour work week. Alternatively, the "consumption equivalent" of the increase in leisure is valued at 8 to 9 percent of total 2003 U.S. consumption expenditures. We also find that leisure increased during the last 40 years for a number of sub-samples of the population, with less-educated adults experiencing the largest increases. Lastly, we document a growing "inequality" in leisure that is the mirror image of the growing inequality of wages and expenditures, making welfare calculation based solely on the latter series incomplete.

Journal ArticleDOI
TL;DR: The authors show that limited investor attention leads to category-learning behavior, i.e., investors tend to process more market and sector-wide information than firm-specific information, which generates important features observed in return comovement that are otherwise difficult to explain with standard rational expectations models.

Journal ArticleDOI
TL;DR: This paper studied the labor market experiences of white male college graduates as a function of economic conditions at time of college graduation and found that cohorts who graduate in worse economies are in lower level occupations and have slightly higher educational attainment.
Abstract: This paper studies the labor market experiences of white male college graduates as a function of economic conditions at time of college graduation. I use the National Longitudinal Survey of Youth whose respondents graduated college between 1979 and 1988 and are followed for 14 to 23 years after college graduation. I employ both national and state variation in economic conditions at time of college graduation to identify the effect. Because timing and location of college graduation could potentially be affected by economic conditions, I also instrument for the national unemployment rate usinf year of birth and for the state unemployment rate using year of birth and state of residence at age 14. I find large, negative wage effects to graduating in a worse economy which persist for the entire period studied. I find that cohorts who graduate in worse economies are in lower level occupations and have slightly higher educational attainment. Labor supply is unaffected.

Posted Content
TL;DR: This article proposed a model that generates an economic expansion in response to good news about future total factor productivity (TFP) or investment-specific technical change, without relying on negative productivity shocks.
Abstract: We propose a model that generates an economic expansion in response to good news about future total factor productivity (TFP) or investment-specific technical change. The model has three key elements: variable capital utilization, adjustment costs to investment, and preferences that exhibit a weak short-run wealth effect on the labour supply. These preferences nest the two classes of utility functions most widely used in the business cycle literature as special cases. Our model can generate recessions that resemble those of the post-war U.S. economy without relying on negative productivity shocks. The recessions are caused not by contemporaneous negative shocks but rather by lackluster news about future TFP or investment-specific technical change.

Journal ArticleDOI
TL;DR: This paper developed a general equilibrium model of multi-product firms and analyzes their behavior during trade liberalization, finding that higher firm-level ability raises a firm's productivity across all products, which induces a positive correlation between a firms' intensive (output per product) and extensive (number of products) margins.
Abstract: This paper develops a general equilibrium model of multi-product firms and analyzes their behavior during trade liberalization. Firm productivity in a given product is modeled as a combination of firm-level "ability" and firm-product-level "expertise", both of which are stochastic and unknown prior to the firm's payment of a sunk cost of entry. Higher firm-level ability raises a firm's productivity across all products, which induces a positive correlation between a firm's intensive (output per product) and extensive (number of products) margins. Trade liberalization fosters productivity growth within and across firms and in aggregate by inducing firms to shed marginally productive products and forcing the lowest-productivity firms to exit. Though exporters produce a smaller range of products after liberalization, they increase the share of products sold abroad as well as exports per product. All of these adjustments are shown to be relatively more pronounced in countries' comparative advantage industries.

Journal ArticleDOI
TL;DR: This article developed a theory of collective beliefs and motivated cognitions, including those concerning money (consumption) and happiness, as well as religion, to explain why most people feel such a need to believe in a "just world" and why this need, and therefore the prevalence of the belief, varies considerably across countries.
Abstract: International surveys reveal wide differences between the views held in different countries concerning the causes of wealth or poverty and the extent to which people are responsible for their own fate. At the same time, social ethnographies and experiments by psychologists demonstrate individuals' recurrent struggle with cognitive dissonance as they seek to maintain, and pass on to their children, a view of the world where effort ultimately pays off and everyone gets their just deserts. This paper offers a model that helps explain: i) why most people feel such a need to believe in a “just world”; ii) why this need, and therefore the prevalence of the belief, varies considerably across countries; iii) the implications of this phenomenon for international differences in political ideology, levels of redistribution, labor supply, aggregate income, and popular perceptions of the poor. The model shows in particular how complementarities arise endogenously between individuals' desired beliefs or ideological choices, resulting in two equilibria. A first, “American” equilibrium is characterized by a high prevalence of just-world beliefs among the population and relatively laissez-faire policies. The other, “European” equilibrium is characterized by more pessimism about the role of effort in economic outcomes and a more extensive welfare state. More generally, the paper develops a theory of collective beliefs and motivated cognitions, including those concerning “money” (consumption) and happiness, as well as religion.

Journal ArticleDOI
TL;DR: This article used three longitudinal data sets of high school graduates in 1957, 1972, and 1992 to understand the narrowing of the gender gap in college and its reversal, finding that from 1972 to 1992 high school girls narrowed the gap with boys in math and science course taking and in achievement test scores.
Abstract: Women are currently the majority of U.S. college students and of those receiving a bachelor's degree, but were 39 percent of undergraduates in 1960. We use three longitudinal data sets of high school graduates in 1957, 1972, and 1992 to understand the narrowing of the gender gap in college and its reversal. From 1972 to 1992 high school girls narrowed the gap with boys in math and science course taking and in achievement test scores. These variables, which we term the proximate determinants, can account for 30 to 60 percent of the relative increase in women's college completion rate. Behind these changes were several others: the future work expectations of young women increased greatly between 1968 and 1979 and the age at first marriage for college graduate women rose by 2.5 years in the 1970s, allowing them to be more serious students. The reversal of the college gender gap, rather than just its elimination, was due in part to the persistence of behavioral and developmental differences between males and females.

Posted Content
TL;DR: This article study the effect of financial restatement on bank loan contracting and find that loans initiated after restatements have significantly higher spreads, shorter maturities, higher likelihood of being secured, and more covenant restrictions.
Abstract: This paper is the first to study the effect of financial restatement on bank loan contracting. Compared with loans initiated before restatement, loans initiated after restatement have significantly higher spreads, shorter maturities, higher likelihood of being secured, and more covenant restrictions. The increase in loan spread is significantly larger for fraudulent restating firms than other restating firms. We also find that after restatement, the number of lenders per loan declines and firms pay higher upfront and annual fees. These results are consistent with the view that banks use tighter loan contract terms to overcome risk and information problems arising from financial restatements.

Journal ArticleDOI
TL;DR: In this paper, the authors present insolvency practitioners from 88 countries with an identical case of a hotel about to default on its debt, and ask them to describe in detail how debt enforcement against this hotel will proceed in their countries.
Abstract: We present insolvency practitioners from 88 countries with an identical case of a hotel about to default on its debt, and ask them to describe in detail how debt enforcement against this hotel will proceed in their countries. We use the data on time, cost, and the likely disposition of the assets (preservation as a going concern versus piecemeal sale) to construct a measure of the efficiency of debt enforcement in each country. We identify several characteristics of debt enforcement procedures, such as the structure of appeals and availability of floating charge finance, that influence efficiency. Our measure of efficiency of debt enforcement is strongly correlated with per capita income and legal origin and predicts debt market development across countries. Interestingly, it is also highly correlated with measures of the quality of contract enforcement and public regulation obtained in other studies.

Journal ArticleDOI
TL;DR: This paper develops an alternative approach to the widely used Difference-In-Difference (DID) method for evaluating the effects of policy changes by introducing a nonlinear model that permits changes over time in the effect of unobservables.
Abstract: This paper develops an alternative approach to the widely used Difference-In-Difference (DID) method for evaluating the effects of policy changes. In contrast to the standard approach, we introduce a nonlinear model that permits changes over time in the effect of unobservables (e.g., there may be a time trend in the level of wages as well as the returns to skill in the labor market). Further, our assumptions are independent of the scaling of the outcome. Our approach provides an estimate of the entire counterfactual distribution of outcomes that would have been experienced by the treatment group in the absence of the treatment, and likewise for the untreated group in the presence of the treatment. Thus, it enables the evaluation of policy interventions according to criteria such as a mean-variance tradeoff. We provide conditions under which the model is nonparametrically identified and propose an estimator. We consider extensions to allow for covariates and discrete dependent variables. We also analyze inference, showing that our estimator is root-N consistent and asymptotically normal. Finally, we consider an application.