market share market value and innovation in a panel of british manufacturing firms this paper examines the empirical relationship between technological innovations market share and stock market value new developments in the estimation of dynamic count data models are used to control for unobserved firm specific heterogeneity we find a robust and positive effect of market share on observable headcounts of innovations and patents although increased product market competition in the industry tends to stimulate innovative activity furthermore the impact of innovation on market value is larger for firms with higher market shares we argue that our results are consistent with models where high market share firms have incentives to pre emptively innovate

using maimonides rule to estimate the effect of class size on scholastic achievement the twelfth century rabbinic scholar maimonides proposed a maximum class size of 40 this same maximum induces a nonlinear and nonmonotonic relationship between grade enrollment and class size in israeli public schools today maimonides rule of 40 is used here to construct instrumental variables estimates of effects of class size on test scores the resulting identiecation strategy can be viewed as an application of donald campbell s regression discontinuity design to the class size question the estimates show that reducing class size induces a signiecant and substantial increase in test scores for fourth and efth graders although not for third graders when asked about their views on class size in surveys parents and teachers generally report that they prefer smaller classes this may be because those involved with teaching believe that smaller classes promote student learning or simply because smaller classes offer a more pleasant environment for the pupils and teachers who are in them mueller chase and walden 1988 social scientists and school administrators also have a longstanding interest in the class size question class size is often thought to be easier to manipulate than other school inputs and it is a variable at the heart of policy debates on school quality and the allocation of school resources in many countries see e g robinson 1990 for the united states ofsted 1995 for the united kingdom and moshel ravid 1995 for israel this broad interest in the consequences of changing class size

market structure firm characteristics and innovative activity in this study the determinants of product innovation by west german firms operating in the metal industry are investigated a strong positive impact of imperfect competition on innovative activity is estimated aside from competition and barriers to entry factors like the ownership structure of a firm internal finance and the skill level of the workforce are considered one result is that firms led by hired managers tend to innovate less intensively than owner managed enterprises copyright 1989 by blackwell publishing ltd

industry and firm specific factors of innovation novelty this article investigates the underlying factors that might shape the firm s choices with respect to degrees of innovation novelty using a sample of 2983 firms observed under the portuguese community innovation survey we assess the relative relevance of a set of firm and industry specific factors in explaining firms choices about incremental or radical innovation the results indicate that both the firm s idiosyncratic historical factors giving rise to heterogeneous r d capabilities and the industry context have power to shape the firm s innovation choices even though firm specific factors appear to be more powerful the estimated impacts on firm s innovation novelty are nonetheless significantly moderated by the type of firm and industry

competition between private and public schools vouchers and peer group effects a theoretical and computational model with tax financed tuition free public schools and competitive tuition financed private schools is developed students differ by ability and income achievement depends on own ability and on peers abilities equilibrium has a strict hierarchy of school qualities and two dimensional student sorting with stratification by ability and income in private schools high ability low income students receive tuition discounts while low ability high income students pay tuition premia tuition vouchers increase the relative size of the private sector and the extent of student sorting and benefit high ability students relative to low ability students

are product and process innovations independent of each other this paper studies the relationship between product and process innovation after discussing the determinants of product and process innovation a simultaneous equation model is estimated a positive impact of product innovation on process innovation can be proved but no evidence for a reverse effect to the respect to the inclusion of product innovation

patent races and the persistence of monopoly patent races are important determinants of market structure for a new firm a patent can be an entry ticket into the market for an incumbent firm already in the market patents for related technologies can ensure that no new firm enters in this spirit recent work has explored the implications of patenting for the persistence of monopoly see for example dasgupta i982 gilbert i98i gilbert and newbery i982 much attention has been given to pre emptive patenting the strategic acquisition of patents by an incumbent firm solely to prevent potential rivals from entering the market in this context it is important to distinguish between two kinds of patent race a standard race is a competition in which a prize is awarded to the first player to reach the finishing line an asymmetrical race is a competition in which one player loses something of value if one of his rivals reaches the finishing line he is content if nobody wins but a prize is won by the first of the other players to reach the finishing line if any of them does so a patent race in which an incumbent firm s sole concern is to prevent potential rivals from entering his market is an asymmetrical race and not a standard race the distinction between the two kinds of race can be captured only in models with a sufficiently rich dynamic structure this and other advantages of a properly dynamic model are explained in section ii a model of an asymmetrical race with two firms is presented in section iii in this model the challenger wins a prize and the incumbent loses a prize if the challenger is first to reach the finishing line it is shown that the challenger is often automatically deterred from making any effort to win the race because the strategic interactions between the players are such that the incumbent would outdo any reasonable effort made by the challenger in order to stop the challenger being first to reach the finishing line then the incumbent has no need to make any effort in the race in order to maintain his existing monopoly the reason is that the incumbent unlike the challenger does not need to go all the way to the finishing line to achieve his objective on the other hand it may be truedepending on the parameters describing the firmsthat the challenger wins the patent proceeding to the finishing line just as if he were the only contender for the patent of particular interest is the case in which the firms are identical

the central role of noise in evaluating interventions that use test scores to rank schools many programs reward or penalize schools based on students average performance mean reversion is a potentially serious hindrance to the evaluation of such interventions chile s 900 schools program p 900 allocated resources based on cutoffs in schools mean test scores this paper shows that transitory noise in average scores and mean reversion lead conventional estimation approaches to overstate the impacts of such programs it further shows how a regressiondiscontinuity design can be used to control for reversion biases it concludes that p 900 had significant effects on test score gains albeit much smaller than is widely believed

a model of the evolution of duopoly does the asymmetry between firms tend to increase or decrease this paper is an attempt to identify some of the factors that affect the evolution of market structure in a model of dynamic competition between two firms the stochastic evolution of the state of competition depends on the respective effort rates of the firms the question is whether the current leader works harder than the laggard does the gap between firms tend to increase or decrease we show that several effects are at work the state tends to evolve in the direction where joint payoffs are greater since joint payoffs are related to joint product market profits less joint effort costs there are two classes of effect the joint profit effect and various joint cost effects the latter result in part from the pattern of profits and in part from endpoint effects that give relief from efforts asymptotic expansions illuminate these influences moreover we show by numerical simulation that there is another kind of joint cost effect the pattern of joint effort costs can influence the pattern of evolution of market structure and the evolution of the pattern of market structure can influence the pattern of efforts in a mutually self reinforcing manner in particular there may be equilibria in which this last effect means that the laggard works harder than the leader even though all the other effects work in favour of the leader

an empirical test of the asymmetric models on innovative activity who invests more into r d the incumbent or the challenger the theoretical discussion concerning the question whether the incumbent or the potential entrant invests more into r d has attracted considerable interest this paper reports the results of an empirical study on this question using data of about 3500 german firms over the years 1992 to 1995 the survey explicitly asks the firms for their motives to undertake innovative activity it is thus possible to take account of intended not just completed market entry it turns out that the challenger invests more into r d in order to enter a new market than the incumbent thus the patent racing model by reinganum and others seems to characterize innovative activity more accurately than the competing auction model of gilbert and newbery we use a heteroscedastic tobit as well as a tobit model with selectivity in order to deal with the econometric problems of double censoring

the size distribution of innovating firms in the uk 1945 1983 a survey of 4 378 significant innovations shows that firms with fewer than 1 000 employees commercialized a much larger share than is indicated by their share of r and d expenditures innovations per employee have been consistently above average in firms with more than 10 000 employees and have become so in firms with fewer than 1 000 intersectoral variation in the size distribution of innovating firms can be explained as a function of r and d based technological opportunities and of technological ease of entry by user firms with principal activities outside the sector copyright 1987 by blackwell publishing ltd

uncertain innovation and persistence of monopoly revisited abstract does monopoly persist in a dynamic industry with opportunities for technological innovations this paper points out that the persistence of monopoly under uncertain innovations depends on how r d competition is modeled if the incumbent and the entrant bid for a stochastic r d technology in an auction framework as in gilbert and newbery american economic review 1982 72 514 526 before engaging in r d competition as in reinganum american economic review 1983 73 741 748 then the incumbent monopolist wins the auction with probability one both for drastic and nondrastic innovations

a general model of r d competition and policy this article constructs a model of r d with heterogeneous firms each firm s probability of success is a function of its sunk and recurrent r d expenditures the social gains from an innovation are not fully captured by the successful firm the comparison of the social optimum and the market equilibrium involves balancing spillover and crowding effects pigovian corrective policies as well as strategic policies for a subset of colluding firms are discussed

innovation and industry evolution the theoretical literature on innovation has been concerned with a single innovation produced by a number of identical agents by contrast we consider a market in which one firm is the current incumbent while the remaining firms are challengers moreover we consider a sequence of innovations so that success does not imply that the successful firm reaps monopoly profits forever after but only until the next better innovation is developed we begin with a fully optimizing behavioral model and derive the equivalent of the schumpeterian process of creative destruction that is a firm enjoys temporary monopoly power but is soon overthrown by a more inventive challenger the essential point to grasp is that in dealing with capitalism we are dealing with an evolutionary process the fundamental impulse that sets and keeps the capitalist engine in motion comes from the new consumers goods the new methods of production or transportation the new markets the new forms of industrial organization that capitalist enterprise creates schumpeter 1942 pp 82 83

good principals or good peers parental valuation of school characteristics tiebout equilibrium and the incentive effects of competition among jurisdictions good principals or good peers parental valuation of school characteristics tiebout equilibrium and the incentive effects of competition among jurisdictions by j esse m r othstein school choice policies may by aligning admin istrators incentives with parental demand yield improved efficiency in educational production milton friedman 1962 john e chubb and terry m moe 1990 but eric a hanushek 1981 cautions if the efficiency of our school systems is due to poor incentives for teachers and admin istrators coupled with poor decision making by consumers it would be unwise to expect much from programs that seek to strengthen market forces in the selection of schools p 35 empha sis added poor decision making is not required parents may rationally choose schools with pleasant surroundings athletic facilities cultural advantages ibid p 34 over those that most efficiently pursue academic performance they may prefer poorly run schools with good peer groups over those that are more effective but en roll worse students j douglas willms and frank h echols 1992 1993 or they may simply be unable to identify effective schools thomas j kane and douglas o staiger 2002 any factor that leads parents to choose any but the most effective available schools will tend to dilute the incentives for efficient management that choice might otherwise create this study examines the distribution of stu dent outcomes across schools within metropol itan housing markets for evidence on parental demand economists have long noted that par ents choices among residential locations are potentially informative about how more com plete choice systems may operate charles m tiebout 1956 melvin v borland and roy m howsen 1992 caroline m hoxby 2000 rothstein 2005 1 i ask whether school effec tiveness plays a sufficiently important role in these decisions to create meaningful incentives for more productive school management i adopt a specific understanding of effective ness appropriate to the question at hand a substantial portion of between school differ ences in student performance can be attributed to differences in student body composition this portion includes the effects of individual stu dent characteristics on their own test scores any direct peer group effects and any indirect ef fects of a school s composition on the quality of its instruction if wealthy schools attract better teachers joseph r antos and sherwin rosen 1975 or more parental involvement this is for my purposes a peer effect it depends on the quality of the school s administration only via school composition a school administrator cannot attract demand by offering a school with wealthy students as these can be offered only if wealthy families demand the school in the first place only the remaining portion of a school s contribution to test scores is effectiveness 2 department of economics and woodrow wilson school princeton university wallace hall 3 rd floor princeton nj 08544 e mail jrothst princeton edu i thank alan auerbach tom davidoff caroline hoxby jus tin mccrary rob mcmillan john quigley cecilia rouse emmanuel saez till von wachter four anonymous refer ees editor robert moffitt seminar participants at several institutions and especially david card for helpful sugges tions i am grateful to the college board for essential data and to a national science foundation graduate research fellowship and the fisher center for real estate and urban economics at uc berkeley for funding see cecilia elena rouse 1998 julie b cullen et al 2005 william g howell et al 2002 and alan b krueger and pei zhu 2004 for analyses of several existing nonresidential choice programs though none focuses on the particular issue studied here this definition avoids the need to find observable de terminants of effectiveness which have proved elusive hanushek 1986 my definition however ignores a school s contribution to nontest outcomes e g sports or music if such outcomes motivate parental choices i will conclude that parents do not demand effective schools of

tax rate effects on interest rates abstract this paper investigates empirically the effects of personal and corporate taxes on taxable interest rates the results suggest that the effective tax rate of marginal investors in the treasury bill market is that of households as opposed to that of tax exempt institutions or corporations

does school choice lead to sorting evidence from tiebout variation a question commonly raised about school choice is whether it would result in sorting or stratification previous research has asked this with respect to inter district or tiebout choice but has generated no consensus in part because areas district concentrations may be endogenous this paper addresses this by exploiting the fact that some metropolitan areas mas have different numbers of districts operating at the primary and the secondary level the resulting within ma between educational level variation in district concentration suggests that increases in district availability do affect children s district and school level peer groups and that they lower private enrollment jel h1 h7 i2

does competition among public schools benefit students and taxpayers tiebout choice among districts is the most powerful market force in american public education naive estimates of its effects are biased by endogenous district formation i derive instruments from the natural boundaries in a metropolitan area my results suggest that metropolitan areas with greater tiebout choice have more productive public schools and less private schooling little of the effect of tiebout choice works through its effect on household sorting this finding may be explained by another finding students are equally segregated by school in metropolitan areas with greater and lesser degrees of tiebout choice among districts

school choice stratification and information on school performance lessons from chile in the early 1980s chile implemented a nationwide school choice system under which the government finances education via a flat per student sub sidy or voucher to the public or private school chosen by a family at present about 94 percent of all schools public religious and secular private are voucher funded more than half of urban schools are private and most of these operate as for profit institutions 1 since the early 1990s chile has also publicized information on school performance and increased per pupil expen diture substantially despite these and other reforms chile has found it challenging to improve students learning outcomes 2 hsieh and urquiola find that the country s rel ative performance in international tests did not change much between 1970 and 1999 3 its performance on the 2000 programme for international student assessment pisa is not only much lower than the oecd average but is similar to that of other latin american countries and low relative to countries with similar income per capita

strategic bidding by potential competitors will monopoly persist who will win the bidding to become the sole producer of a new product the monopolist of a related product or a new entrant when there exists potential entry to the monopolist s existing business the standard result that monopoly persists gilbert and newbery preemptive patenting and the persistence of monopoly american economic review 72 pp 514 526 1982 may or may not hold depending crucially on how the new product relates to the existing product of the monopolist the monopolist tends to win the bidding and to dominate both products if the two products are strategic complements and the entrant tends to win the bidding if the two products are strategic substitutes

innovation and firm growth does firm age play a role this paper explores the relationship between innovation and firm growth for firms of different ages we hypothesize that young firms undertake riskier innovation activities which may have greater performance benefits if successful or greater losses if unsuccessful using an extensive spanish community innovation survey sample for the period 2004 2012 we apply panel quantile regressions to study the effect of r d activities on firm growth i e sales growth productivity growth and employment growth our results show that young firms face larger performance benefits from r d at the upper quantiles of the growth rate distribution but face larger decline at the lower quantiles r d investment by young firms therefore appears to significantly riskier than r d investment by more mature firms which suggests some policy implications

private school vouchers and student achievement an evaluation of the milwaukee parental choice program in 1990 wisconsin began providing vouchers to a small number of low income students to attend nonsectarian private schools controlling for individual fixed effects i compare the test scores of students selected to attend a participating private school with those of unsuccessful applicants and other students from the milwaukee public schools i find that students in the milwaukee parental choice program had faster math score gains than but similar reading score gains to the comparison groups the results appear robust to data imputations and sample attrition although these deficiencies of the data should be kept in mind when interpreting the results

school vouchers a survey of the economics literature we review the theoretical computational and empirical research on school vouchers with a focus on the latter our assessment is that the evidence to date is not sufficient to warrant recommending that vouchers be adopted on a widespread basis however multiple positive findings support continued exploration specifically the empirical research on small scale programs does not suggest that awarding students a voucher is a systematically reliable way to improve educational outcomes and some detrimental effects have been found nevertheless in some settings or for some subgroups or outcomes vouchers can have a substantial positive effect on those who use them studies of large scale voucher programs find student sorting as a result of their implementation although of varying magnitude evidence on both small scale and large scale programs suggests that competition induced by vouchers leads public schools to improve moreover research is making progress on understanding how vouchers may be designed to limit adverse effects from sorting while preserving positive effects related to competition finally our sense is that work originating in a single case e g a given country or in a single research approach e g experimental designs will not provide a full understanding of voucher effects fairly wide ranging empirical and theoretical work will be necessary to make progress

dropout behavior in r d races with learning we examine a game theoretic model of a two firm r d race in which expenditures on r d and the concomitant increase in experience learning enable thefirms to increase their probability of discovering an invention the learning process is stochastic it generates a unique subgame perfect equilibrium for identicalfirms with the characteristic that the leader never drops out but the follower drops out if the leader gains a significant lead the leader can find it optimal to drop out if the firms value the invention differently or have different r d efficiencies thus our analysis generates results between vigorous competition and natural monopoly central to schumpeter s 1934 vision of entrepreneurship are the extraordinary profits associated with innovation the lure of these profits fuels the fires of creative destruction as innovators replace declining firms this article analyzes the competition for the profits obtained by bringing an innovation to fruition and receiving the associated patent we restrict attention to the subclass of innovations known as inventions innovations that are the product of a firm s research and development in particular we are concerned with the conditions that cause a firm after having invested in r d to drop out of the competitive race situations in which the leading firm drops out are of even greater interest competition in r d is often modelled as a race in which the winner receives a patent and reaps most or all of the benefits of the invention as exemplified by kamien and schwartz 1972 the early theoretical literature tended to be based on decision theoretic models the firm seeks an optimal rate of expenditure on r d determined in part by the expected value of the invention the extent of the first mover advantage the economies or diseconomies of scale in r d and the perceived intensity of rivalry it is not anticipated that the firm s decisions will affect the r d efforts of the perhaps unknown rivals kamien and schwartz 1982 p 124 show that the firm does no research if rivalry is sufficiently intense because their model is static however it is never the case that a firm enters the race and then drops out

customer power strategic investment and the failure of leading firms why might firms be regarded as astutely managed at one point yet subsequently lose their positions of industry leadership when faced with technological change we present a model grounded in a study of the world disk drive industry that charts the process through which the demands of a firm s customers shape the allocation of resources in technological innovation a model that links theories of resource dependence and resource allocation we show that established firms led the industry in developing technologies of every sort even radical ones whenever the technologies addressed existing customers needs the same firms failed to develop simpler technologies that initially were only useful in emerging markets because impetus coalesces behind and resources are allocated to programs targeting powerful customers projects targeted at technologies for which no customers yet exist languish for lack of impetus and resources because the rate of technical progress can exceed the performance demanded in a market technologies which initially can only be used in emerging markets later can invade mainstream ones carrying entrant firms to victory over established companies

the degree of fiscal illusion in interest rates some direct estimates this article demonstrates why the procedures used in previous studies do not permit inference about the relationship between interestrates and taxes we present a model that leads to direct estimates of the degree to which interest rates respond to changes in tax rates the empirical results imply that the adjustment of taxable interest rates has been large enough to render after tax yields impervious to tax rate changes further tax exempt yields are unaffected by changes in taxrates thus there is no evidence of fiscal illusion in interest rates this abstract was borrowed from another version of this item

r d rivalry with licensing or imitation the authors study the rivalry between two firms to develop an innovation in a dynamic setting that allows for post development dissemination of the innovation such as licensing or imitation this dissemination may cause the noninnovating firm to benefit from the discovery when this occurs conventional results in the economics of r d no longer need apply they find that industry leaders will tend to develop minor innovations but will develop major innovations only if imitation is difficult copyright 1987 by american economic association

preemptive patenting and the persistence of monopoly this article takes a different tack and inquires whether institutions such as the patent system create opportunities for firms with monopoly power to maintain their monopoly power the results apply to other situations such as brand identification spatial location and capacity expansion which share the characteristic that early or preemptive actions may lower the returns to potential competitors

the strugglers the new poor in latin america summary we identify a group of people in latin america that are not poor but not middle class either namely strugglers in households with daily income per capita between 4 and 10 at constant 2005 ppp this group will account for about a third of the region s population over the next decades as the size and income of the middle class rises they could become increasingly marginalized the cash transfers they receive are largely offset by indirect taxes the benefit of schooling and other in kind transfers they receive is questionable after adjusting for quality we discuss implications for the social contract

the promise and pitfalls of using imprecise school accountability measures in recent years most states have constructed elaborate accountability systems using school level test scores however because the median elementary school contains only 69 children per grade level such measures are quite imprecise we evaluate the implications for school accountability systems for instance rewards or sanctions for schools with scores at either extreme primarily affect small schools and provide weak incentives to large ones nevertheless we conclude that accountability systems may be worthwhile even in states with aggressive financial incentives the marginal reward to schools for raising student performance is a small fraction of the potential labor market value for students

estimating the effect of financial aid offers on college enrollment a regression discontinuity approach an important problem faced by colleges and universities that of evaluating the effect of their financial aid offers on student enrollment decisions is complicated by the likely endogeneity of the aid offer variable in a student enrollment equation this article shows how discontinuities in an east coast college s aid assignment rule can be exploited to obtain credible estimates of the aid effect without having to rely on arbitrary exclusion restrictions and functional form assumptions semiparametric estimates based on a regression discontinuity rd approach affirm the importance of financial aid as an effective instrument in competing with other colleges for students

assessment of the public tools used to promote r d investment in spanish smes in this paper we identify the potential determinants of firm r d to understand the effectiveness of public policies our results suggest a considerably low impact of tax credits and public grants on the r d investment of the spanish manufacturing firms tax credits are mainly considered by large firms that use them as a reduction in the tax burden in the corporate tax while smes use public grants to alleviate financial constraints this evidence leads to discuss alternatives to the current design of the public policies analyzed

disruption versus tiebout improvement the costs and benefits of switching schools most students change schools at some point in their academic careers but some change very frequently and some schools experience a great deal of turnover while many argue that mobility harms students economists tend to emphasize tiebout type moves to procure better school quality sq this paper disentangles the disruption effects of moves from changes in sq importantly it identifies the negative externality movers impose on other students student turnover is shown to entail a substantial cost for movers and non movers alike this cost appears to be larger for lower income and minority students who typically attend much higher turnover schools

vouchers for private schooling in colombia evidence from a randomized natural experiment colombia used lotteries to distribute vouchers which partially covered the cost of private secondary school for students who maintained satisfactory academic progress three years after the lotteries winners were about 10 percentage points more likely to have finished 8th grade primarily because they were less likely to repeat grades and scored 0 2 standard deviations higher on achievement tests there is some evidence that winners worked less than losers and were less likely to marry or cohabit as teenagers benefits to participants likely exceeded the 24 per winner additional cost to the government of supplying vouchers instead of public school places

practical implications of game theoretic models of r and d the purpose of this paper is to survey recent game theoretic models of research and development and to ask whether they yield practical implications or testable hypotheses the papers i will be discussing have been written or published within the past five years they have a good deal in common relying upon similar assumptions and building upon each other because of this the literature surveyed here may seem narrow and some relevant work has probably been inadvertently omitted i apologize for these omissions for want of space i will not discuss the normative conclusions of this literature

the sensitivity of strategic and corrective r d policy in battles for monopoly the authors characterize the role for r d subsidies in export markets where r d is an uncertain process and the winner of the r d competition monopolizes the market investments are assumed to induce either first order or mean preserving second order shifts in the distribution of a firm s costs or reinterpreting the model as a patent race a firm s discovery dates the authors show that regardless of which form the uncertainty takes a national strategic incentive to subsidize r d exists but must be balanced against a national corrective incentive to tax r d whenever a country has multiple firms involved in the r d competition copyright 1992 by economics department of the university of pennsylvania and the osaka university institute of social and economic research association

dynamic r d competition the authors study a simple two stage stochastic patent race involving two firms they examine the behavior of the participants as they gain the lead or fall behind in the race the authors find that the leader engages in rd 2 a policy of issuing patents for intermediate research results and 3 the effects of research joint ventures whereby the firms coordinate their initial research efforts and share their results copyright 1987 by royal economic society

a dynamic oligopoly with collusion and price wars we provide a collusive framework with heterogeneity among jirms investment entry and exit it is a symmetric information model in which it is hard to sustain collusion when there is an activejim that is likely to exit in the near future numerical analysis is used to compare a collusive to a noncollusive environment only the collusive industry generates price wars also the collusive industry offers both more and higherquality products to consumers albeit often at a higher price the positive effect of collusion on variety and quality more than compensates consumers for the negative effect of collusive prices so that consumer surplus is larger with collusion

the role of sunk costs in the decision to invest in r d we present a dynamic empirical model of a firm s r d decisions that is consistent with the existence of sunk r d costs taking into account that these costs may differ between small and large firms and among different technological regimes we estimate a multivariate dynamic discrete choice model using firm level data of spanish manufacturing for 1990 2000 conditional on firm heterogeneity and serially correlated unobservable factors we find that r d history matters this true state dependence allows inferring the existence of sunk r d costs associated with performing r d sunk r d costs are found to be higher for large high tech firms

the effects of generalized school choice on achievement and stratification evidence from chile s voucher program in 1981 chile introduced nationwide school choice by providing vouchers to any student wishing to attend private school as a result more than 1000 private schools entered the market and the private enrollment rate increased by 20 percentage points with greater impacts in larger more urban and wealthier communities we use this differential impact to measure the effects of unrestricted choice on educational outcomes using panel data for about 150 municipalities we find no evidence that choice improved average educational outcomes as measured by test scores repetition rates and years of schooling however we find evidence that the voucher program led to increased sorting as the bbestq public school students left for the private sector d 2005 elsevier b v all rights reserved

estimation of a labour supply model with censoring due to unemployment and underemployment this study proposes and implements a method of labour supply estimation which is appropriate when the sample contains unemployed and underemployed workers the estimation method consists of excluding unemployed and underemployed workers from the sample and then using to avoid selection bias an extension of heckman s approach to the case where two correlated selection rules generate the sample hausman s specification test is then used to determine whether ignoring constrained workers has led to biases in traditional labour supply estimates and the empirical results suggest that previous estimates of several important parameters are biased since the biases go in the direction that would be predicted by the hypothesis that the unemployed and underemployed are constrained the results support this hypothesis