an empirical study on taiwan s current account 1961 90 in this paper a simple intertemporal current account model is developed for a small open economy with imperfect capital markets the model nests both perfect and imperfect international capital mobilities as its special cases the model is empirically examined using taiwan s annual data for the period between 1961 and 1990 our results show that the model is able to explain some historical movements of taiwan s trade balance however in contrast to many findings from previous studies for other countries the model is rejected one important feature of the rejection of the model is that the actual trade balance series is much more volatile than can be explained by the model this is especially so for the periods when world oil shocks occurred these results indicates that changes in the terms of trade which our simple model neglects might be important factors in taiwan s current determination

wealth accumulation over the life cycle and precautionary savings this article constructs and simulates a life cycle model of wealth accumulation and estimates the parameters of the utility function the rate of time preference and the coefficient of risk aversion by matching the simulated median wealth profiles with those observed in the panel study of income dynamics and in the survey of consumer finances the estimates imply a low degree of patience and a high degree of risk aversion the results are used to study the importance of precautionary savings in explaining wealth accumulation they imply that wealth accumulation is driven mostly by precautionary motives at the beginning of the life cycle whereas savings for retirement purposes become significant only closer to retirement

comparing consumption based asset pricing models we make use of a recently developed method to estimate the intertemporal mar ginal rate of substitution consistent with the fluctuations of asset return data from the toronto stock exchange these estimates are then used to evaluate various parametric specifications for preferences often used in empirical studies of consumption and asset returns in contrast to existing studies we are able to perform a formal statistical comparison of these models we consider six extensions of the usual power utility model and we find that none can be said to be a demonstrable improvement on the standard model

the hyperbolic consumption model calibration simulation and empirical evaluation ur preferences for the long run tend to conflict with our short run behavior when planning for the long run we intend to meet our deadlines exercise regularly and eat healthfully but in the short run we have little interest in revising manuscripts jogging on the stairmaster and skipping the chocolate souffleala mode delay of gratification is a nice long term goal but instant gratification is disconcertingly tempting this gap between long run intentions and short run actions is apparent across a wide range of behaviors including saving choices a 1997 survey found that 76 percent of respondents believe they should be saving more for retirement looking only at respondents who believed they were at an age where you should be seriously saving already the survey found that 55 percent reported being behind in their savings and only 6 percent reported being ahead farkas and johnson 1997 the report on the survey concluded t he gaps between people s atti tudes intentions and behavior are troubling and threaten increased insecurity and dissatisfaction for people when they retire americans are simply not doing what logic and their own reasoning suggests they should be doing a 1993 luntz webber merrill lynch survey found similar answers when baby boomers were asked what percentage of your annual household income do you think you should save for retirement and what percentage of your annual

airport congestion when carriers have market power this paper analyzes airport congestion when carriers are nonatomistic showing how the results of the road pricing literature are modified when the economic agents causing congestion have market power the analysis shows that when an airport is dominated by a monopolist congestion is fully internalized yielding no role for congestion pricing under monopoly conditions under a cournot oligopoly however carriers are shown to internalize only the congestion they impose on themselves a toll that captures the uninternalized portion of congestion may then improve the allocation of traffic the analysis is supported by some rudimentary empirical evidence

distributional consequences of airport congestion pricing abstract imposition of airport congestion pricing redistributes welfare among commercial regional and general aviation this article extends daniel s econometrica63 327 370 1995 stochastic bottleneck model with dynamically adjusting traffic rates queuing delays and congestion fees to include elastic demand heterogeneous operating time preferences and heterogeneous layover and queuing time values using parameters from minneapolis st paul airport simulations of congestion pricing determine its effects on equilibrium traffic patterns queuing delays schedule delays airport revenues and social welfare gains by commercial aviation common travelers and airport authorities exceed losses by general and regional aviation the article evaluates several price and rebate programs and proposes several that are self financing and pareto improving

u s fiscal policy and trade deficits a broad perspective the emergence of large government budget deficits and large international trade deficits stands out as the dominant feature of u s macroeconomic behavior since the early 1980s economists trained in the traditional keynesian theory have pointed to the budget deficit as the major cause of the trade deficit according to the mundell fleming model changes in the budget deficit trigger changes in the real interest rate the real exchange rate and the level of real income which in turn alter the trade balance others believing in the real world relevance of the ricardian equivalence proposition have argued that the deficits are not really twins but merely distant cousins if not entirely unrelated if ricardian equivalence holds shifts between taxes and borrowing have no effect on real interest rates or aggregate demand previous studies of the twin deficits have adopted a variety of approaches both theoretical and empirical theoretical treatments run the gamut from the standard mundell fleming model 18 to the ricardian model 7 to the atheoretical 1 2 3 4 12 14 17 empirical approaches range from simple single equation ols 5 6 16 to two stage least squares applied to a system of structural equations 18 to unconstrained var modeling 1 2 12 17 to cointegration 3 14 the variables used to measure the budget and trade deficits vary across studies as does the set of related variables included in the models the form in which the data are utilized e g as a ratio of gnp or as a first difference of levels also differs across studies not surprisingly a variety of results emerges table i provides a brief overview of a number of studies the estimated effects of budget deficits on the trade balance range from the substantial 12 to statistically insignificant 7 abell 1 2 finds the transmission mechanism to be primarily through interest and exchange rates while zietz and pemberton 18 find that channel to be insignificant in comparison to the domestic absorption channel yet some studies do not even include domestic income as a separate variable in their equations making cross study comparisons difficult thus it is impossible to draw with confidence any conclusions about the twin deficits relationship this confusion of results leads us to examine systematically the relationship between the two deficits using a multivariate model in this paper we report the results of a systematic analysis of the link between the deficits using a five variable system for the flexible exchange rate period 1973 1 to 1991 iv we begin with

the nature of precautionary wealth abstract this paper uses the panel study of income dynamics to provide some of the first direct evidence that wealth is systematically higher for consumers with predictably greater income uncertainty however the apparent pattern of precautionary wealth is not consistent with a standard parameterization of the life cucle model in which consumers are patient enough to begin saving for retirement early in life wealth is estimated to be far less sensitive to uncertainty than implied by that model instead our results suggest that over most of their working life time consumers behave in accordance with the buffer stock models of saving described in carroll 1992 1997 or deaton 1991 in which consumers hold wealth principally to insulate consumption against near term fluctuations in income

precautionary savings and the self employed this work focuses on the impact of uncertainty on savings under bequest form specifically we estimate whether and to what extent income variability does have an effect on post mortem savings we approximate the post mortem savings with the closest dedicated savings which is savings in term insurance a lump sum inherited at the death of the subscriber furthermore we test whether the intensity of the income variance or the riskiness of the job type such as self employment matters more in the choice our results show that self employment status is one of the most relevant variables affecting term insurance ownership

congestion pricing and capacity of large hub airports a bottleneck model with stochastic queues this paper models and estimates congestion prices and capacity for large hub airports the model includes stochastic queues time varying traffic rates and endogenous intertemporal adjustment of traffic in response to queuing delay and fees relative costs of queuing and schedule delays are estimated using data from minneapolis st paul simulations calculate equilibrium traffic patterns queuing delays schedule delays congestion fees airport revenues airport capacity and efficiency gains the paper also investigates whether a dominant airline internalizes delays its aircraft impose it tests game theoretic specifications with atomistic nash dominant stackelberg dominant and collusive airline traffic

the twin deficits phenomenon evidence from greece this paper explores the relationship between budget and trade deficits in a small open economy using annual data the purpose of the paper is to test empirically the validity and rationale of the keynesian proposition conventional view and the ricardian equivalence hypothesis the econometric methodology is based on cointegration analysis error correction modelling and granger trivariate causality the ecm empirical findings suggest that budget deficit has short and long run positive and significant causal effects on trade deficit

twin sons of different mothers the long and the short of the twin deficits debate i introduction the relationship between the government budget deficit and the current account deficit has been a contentious subject in empirical macroeconomics for at least the past 20 yr papers have variously found a positive link no link and three recent pieces even find a negative link between the two there are however some things that almost all these studies have in common for example they ignore the possibility of structural breaks in the series when examining their time series properties most previous studies treat the variables under study as being integrated of order 1 which is to say as having a unit root this is a hard assumption to square with the fact that the variables are measured as fractions of gross domestic product gdp and have over the last half century at least shown no inclination toward typical unit root behavior by contrast in three recent pieces corsetti and muller 2006 kim and roubini 2008 muller 2006 the two series are simply treated as pure stationary processes without any pretesting which obviously conflicts with results from the traditional unit root tests in this article we show that both the budget deficit and the current account deficit are stationary around an occasionally shifting mean which is to say that they have structural breaks but are stationary after allowing for those breaks since it is well known that traditional unit root tests have little power when the underlying data contain structural breaks this explains the puzzling finding that the budget deficit and the current account deficit expressed as fractions of gdp test out as i 1 series in practice our findings also cast doubt on the validity of assuming the two series are purely stationary processes given our framework a simple test for the existence of a long run equilibrium relationship between budget and current account deficits is to compare the number and timing of their structural shifts we find that the two series are not closely related either in their number of breaks or in their timing of structural shifts we thus conclude that over the long run genetically the deficits are not twins another factor that existing studies have in common is their treatment of the error structure of the model as homoskedastic despite relatively clear visual evidence of volatility clustering conditional heteroskedasticity in least squares residuals when we consider the short run dynamics of the demeaned variables through a vector autoregression var analysis we show that the error covariance of this var model is significantly conditionally heteroskedastic and go on to specifically account for this phenomenon with a var generalized autoregressive conditional heteroskedasticity garch model we consider a trivariate model that also includes the real interest rate here we find a significant and sizeable positive short run effect of budget deficit innovations on the current account deficit in both the impulse response functions and the variance decompositions of the model our answer to the question of the paternity of the two deficits thus depends on the horizon studied each series has structural breaks that are largely independent of each other so they are not twins at all over the long run however once we allow for these secular shifts the short run dynamics reveal a very strong family resemblance indeed the rest of the article is organized as follows in section ii we review some of the existing empirical literature section iii discusses the time series properties of the data and presents our results about the long run evidence on the twin deficits question section iv sets out our var garch model and presents our results on short run twin deficits behavior section v is a brief conclusion ii an overview of the empirical literature the relationship between current account deficits and government budget deficits has been a subject of extensive study

congestible facility rivalry in vertical structures abstract this paper investigates rivalry between congestible facilities and its effects on facility charges capacities and congestion delays by incorporating the downstream carriers into the analysis we find that i the duopoly facilities have lower prices than the monopolist but they offer lower service quality only if capacity decisions are made prior to facility price decisions when the capacity and price decisions are made simultaneously the duopolists will provide the same service quality as the monopolist ii conditional on facility charges the monopolist will have the same capacity investment rules as the central planner if and only if the downstream carrier markets are perfectly competitive at both facilities if there is one carrier market that is imperfectly competitive the monopoly capacity rules will be different from the socially optimal capacity rules iii the monopolist will offer the same service quality at a facility as the central planner if the carrier market is perfectly competitive otherwise the monopolist offers a higher service level than the central planner we also find that for given capacities a the duopolists equilibrium prices increase with the time costs of either consumers or carriers b entrance of a new carrier to any of the facilities depresses the prices charged by both facilities and c lower marginal cost of the carriers at one facility induces a higher price at that facility but a lower price at the other facility

transitory and permanent disturbances and the current account an empirical analysis in the intertemporal framework the intertemporal models of current account determination demonstrate that in the analysis of the current account balance of a country it is important to distinguish between transitory and permanent disturbances in income and relative prices this paper attempts to decompose the observed data on income and real exchange rate into transitory and permanent components and then uses the decomposed series to test the empirical validity of the predictions of the intertemporal models evidence from the united states and japan provide very limited support for the intertemporal models in terms of the effects of transitory and permanent changes in income on current account balance for both us and japan the study finds that permanent changes in real exchange rate have significant effects on the current account balance statistical tests find no evidence of hysteresis in the trading relations of the two countries

a theory of the consumption function with and without liquidity constraints fifteen years ago milton friedman s 1957 treatise a theory of the consumption function seemed badly dated dynamic optimization theory had not been employed much in economics when friedman wrote and utility theory was still comparatively primitive so his statement of the permanent income hypothesis never actually specified a formal mathematical model of behavior derived explicitly from utility maximization instead friedman relied at crucial points on intuition and verbal descriptions of behavior although these descriptions sounded plausible when other economists subsequently found multiperiod maximizing models that could be solved explicitly the implications of those models differed sharply from friedman s intuitive description of his model furthermore empirical tests in the 1970s and 1980s often rejected these rigorous versions of the permanent income hypothesis in favor of an alternative hypothesis that many households simply spent all of their current income today with the benefit of a further round of mathematical and computational advances friedman s 1957 original analysis looks more prescient than primitive it turns out that when there is meaningful uncertainty in future labor income the optimal behavior of moderately impatient consumers is much better described by friedman s original statement of the permanent income hypothesis than by the later explicit maximizing versions furthermore in a remarkable irony much of the empirical evidence that rejected the permanent income hypothesis as specified in tests of the 1970s and 1980s is actually consistent both with friedman s original description of the model and with the new version with serious uncertainty there are four key differences between the explicit maximizing models

saving and liquidity constraints this paper is concerned with the theory of saving when consumers are not permitted to borrow and with the ability of such a theory to account for some of the stylized facts of saving behavior the models presented in the paper seem to account for important aspects of reality that are not explained by traditional life cycle models copyright 1991 by the econometric society

optimal pricing of flights and passengers at congested airports and the efficiency of atomistic charges abstract this paper investigates and compares airport pricing policies under various types of competition considering both per passenger and per flight charges at congested airports we show that an airport requires both pricing instruments to achieve the first best outcome and we distinguish their role by showing that congestion externalities need to be addressed through per flight tolls whereas the inefficiency caused by airlines market power exertion must be corrected with per passenger subsidies we also show that bertrand competition with differentiated products a type of behavior recently pointed out by the empirical literature as pertinent has policy implications that diverge from analyses that assume cournot competition the welfare gains and congestion reductions of congestion pricing would be higher than what has been advanced before the degree of self financing of airport infrastructure under optimal pricing would be increased and may approach exact self financing and the implied differentiation of charges between asymmetric airlines would be significantly smaller presumably enhancing the political feasibility of welfare maximizing congestion pricing as the potential distributional concerns would be decreased finally we numerically analyze second best policies and find that atomistic pricing may offer a relatively attractive alternative to first best congestion pricing

atomistic congestion tolls at concentrated airports seeking a unified view in the internalization debate abstract the goal of this paper is to bring some unity to the theoretical side of the debate on internalization of airport congestion by showing that all the literature s theoretical results can be derived within one simple and unified framework the analysis starts by replicating the results of brueckner brueckner j k 2002 airport congestion when carriers have market power american economic review 92 1357 1375 who showed that because airlines behaving in cournot fashion internalize congestion they should be charged low congestion tolls the analysis then validates the findings of daniel daniel j i 1995 congestion pricing and capacity of large hub airports a bottleneck model with stochastic queues econometrica 63 327 370 who argued that larger atomistic tolls are required in a model where a stackelberg leader interacts with competitive fringe airlines however it is shown that this result only holds approximately when the carriers outputs are imperfect substitutes

life cycle individual thrift and the wealth of nations this paper provides a review of the theory of the determinants of individual and national thrift that has come to be known as the life cycle hypothesis lch of saving applications to some current policy issues are also discussed part i deals with the state of the art on the eve of the formulation of the lch some 30 years ago part ii sets forth the theoretical foundations of the model in its original formulation and later amendment calling attention to various implications distinctive to it and sometimes counter intuitive it also includes a review of a number of crucial empirical tests both at the individual and the aggregate level part iii reviews some applications of lch to current policy issues though only in sketchy fashion as space constraints prevent fuller discussion this abstract was borrowed from another version of this item

how do politicians save buffer stock management of unemployment insurance finance abstract we fit an empirical structural model of forward looking government savings behavior to data from the u s state unemployment insurance ui programs 1976 2008 states increase benefits or lower taxes when unemployment trust fund balances are high consistent with a desired target level of savings this can be explained by the representative state program behaving like a carroll 1992 buffer stock consumer who trades off a desire to expend savings impatience against the fear of running out of funds risk aversion we calibrate the model to the data and find that statistics from model simulations match similar statistics produced from the data for reasonable levels of risk aversion and impatience

does the quality of institutions enhance savings the case of sub saharan africa over the last three decades there has been increasing disparity in savings across regions and income groupings globally in this paper we investigate whether the quality of institutions explains

humps and bumps in lifetime consumption in this article we argue that the life cycle model that allows demographics to affect household preferences and relaxes the assumption of certainty equivalence can generate hump shaped consumption profiles over age that are very similar to those observed in household level data sources and in particular match the differences in shape across different education groups liquidity constraints or myopia are not required to explain the empirical features of observed life cycle patterns

airline network rivalry in this paper the effects of the strategic interaction between deregulated airlines on their network choice are analyzed the authors examine whether switching from a linear to a hub spoke network confers a strategic advantage because it saves costs and improves service quality they find that if hubbing lowers total cost which includes both airline and passenger inconvenience costs the pursuit of strategic advantages usually intensifies the extent of hubbing even if hubbing raises total cost it might be pursued by the airline either because hubbing is a dominant strategy in an oligopolistic setting or because hubbing will be useful in deterring entry

economics and electronic commerce for economists who study markets whether wholesale or retail goods or services commodities or highly differentiated products these are extraordinary times the internet and related technologies have caused the costs of many kinds of market interactions to plummet as with any dramatic technological change the most obvious and earliest effects are incremental we find easier and less costly ways of doing the things we are already doing over time however the shifts are more drastic we discover that we can do entirely new things or completely restructure the way in which certain business activities are carried out such long term impacts of technological change are always hard to forecast but that task is especially difficult in the case of e commerce where markets are currently very far from equilibrium in the land rush to secure internet real estate to gain first mover market position and other advantages many firms are pursuing strategies that are properly interpreted as the payment of one time largely sunk entry costs in some cases the focus of these expenditures is on customer acquisition through pricing that is not likely to be sustainable while in others it is building infrastructure to achieve minimum efficient scale these expenditures fueled by inflows of venture capital may represent reasonable investments for a chance of a future stream of profits that might accrue to the

interest rates and expected future budget deficits in the united states several recent empirical studies have found no evidence of a positive association between interest rates and current and past budget deficits one possible explanation for this finding is that interest rates are related much more to the expectation of future budget deficits than to current and past budget deficits in this paper i investigate whether this explanation is valid finding no evidence that it is section ii briefly formulates and discusses the hypothesis under consideration stating some of its implications section iii presents the results of regressing the commercial paper rate moody s aaa bond rate and the ex post real commercial paper rate on current and past government spending budget deficits and real money supplies the regressions have been fitted to the entire sample of monthly data spanning the period between june 1908 and march 1984 and to 11

the effect of air traffic delays on airline prices abstract a legislative change in takeoff and landing restrictions at laguardia airport provides an opportunity to study the effect of an exogenous shock to product quality on prices in the airline industry i test how the price response varies with the degree of competition in the market i find that prices fall by 1 42 on average for each additional minute of flight delay and that the price response is substantially larger in more competitive markets

winning or losing from dynamic bottleneck congestion pricing the distributional effects of road pricing with heterogeneity in values of time and schedule delay abstract this paper analyses the efficiency and distributional impacts of congestion pricing in vickrey s 1969 dynamic bottleneck model of congestion allowing for continuous distributions of values of time and schedule delay we find that congestion pricing can leave a majority of travellers better off even without returning the toll revenues to them we also find that the consumer surplus losses or gains from tolling are not strictly monotonic in the value of time because they also depend on the value of schedule delays the greatest losses are not incurred by drivers with the lowest value of time but by users with an intermediate value of schedule delays and the lowest value of time for that value of schedule delays for second best pricing with an untolled alternative the pattern of distributional effects is quite similar to that for first best pricing in contrast with results from prior static models users who are indifferent between the two alternative routes are not the ones who gain least from this type of second best pricing our results suggest that in assessing the distributional impacts of road congestion pricing it is important to take into account both the distribution of the value of time and of the value of schedule delays as well as the dynamics of departure time choice

pricing the major us hub airports abstract implementing congestion pricing at 27 major us airports would reduce delays by 13 passenger years and 1000 aircraft hours every day saving 3 5 million dollars daily chicago and atlanta would save about 1000 dollars per aircraft airport revenues would increase about 11 million dollars daily a bottleneck model with stochastic queues estimates substantial welfare gains whether or not airlines internalize self imposed delays erroneously imposing fees from the non internalizing specification on internalizing airlines however would be a costly mistake the model calculates equilibrium traffic rates queuing delays layover times connection times and congestion fee schedules by minute of the day

current account and budget deficits twins or distant cousins the paper develops a two country micro theoretic model consistent with the ricardian equivalence hypothesis reh specifically tax increases used to retire government debt will not affect private spending or the current account balance however increases in government spending regard less of the means of finance can be expected to induce a current account deficit an unconstrained vector autoregres sion shows some patterns in the recent u s data which appear to be inconsistent with the reh rigorous testing of the model however does not allow us to reject the indepen dence of the record federal government budget and current account deficits

the economics of airport congestion pricing abstract conventional economic wisdom suggests that congestion pricing would be an appropriate response to cope with the growing congestion levels currently experienced at many airports several characteristics of aviation markets however may make naive congestion prices equal to the value of marginal travel delays a non optimal response this paper develops a model of airport pricing that captures a number of these features the model in particular reflects that 1 airlines typically have market power and are engaged in oligopolistic competition at different sub markets 2 part of external travel delays that aircraft impose are internal to an operator and hence should not be accounted for in congestion tolls and 3 different airports in an international network will typically not be regulated by the same authority we present an analytical treatment for a simple two node network and some numerical results to illustrate our findings some main conclusions are that second best optimal tolls are typically lower than what would be suggested by congestion costs alone and may even be negative and that cooperation between regulators need not be stable but that non cooperation may lead to welfare losses also when compared to a no tolling situation

airlines strategic interactions and airport pricing in a dynamic bottleneck model of congestion abstract this paper analyzes efficient pricing at a congested airport dominated by a single firm unlike much of the previous literature we combine a dynamic bottleneck model of congestion and a vertical structure model that explicitly considers the role of airlines and passengers we show that a stackelberg leader interacting with a competitive fringe partially internalizes congestion and that there are various toll regimes that induce the welfare maximizing outcome widening the set of choices for regulators in particular charging the congestion toll that would apply for fully competitive carriers and that ignores any internalization to both the leader and the fringe yields the first best outcome

price vs quantity based approaches to airport congestion management abstract this paper analyzes price and quantity based approaches to management of airport congestion using a model where airlines are asymmetric and internalize congestion under these circumstances optimal congestion tolls are differentiated across carriers and a uniformity requirement on airport charges as occurs when slots are sold or tolls are uniform distorts carrier flight choices flight volumes tend to be too low for large carriers and too high for small carriers but quantity based regimes where the airport authority allocates a fixed number of slots via free distribution or an auction lead carriers to treat total flight volume and thus congestion as fixed and this difference generates an efficient outcome as long as the number of slots is optimally chosen

the life cycle model of consumption and saving a central implication of life cycle models is that agents smooth consumption we review the empirical evidence on smoothing at frequencies from within the year up to across a lifetime we find that life cycle models particular those which incorporate realistic features of markets and goods have more empirical successes than failures we also show that some apparent deviations from theoretical predictions imply very small welfare losses for agents finally we emphasize that the coherence of life cycle models imposes an important discipline when incorporating new features into models

the political economy of deficit spending in nine industrialized parliamentary democracies the role of fiscal institutions this article analyzes the influence of four sets of factors on deficit spending in 9 industrialized parliamentary democracies during 1958 1990 this article analyzes the influence of these factors and introduces and tests the importance of an additional potential influence on the size of a country s fiscal deficit the strength of fiscal bureaucracy it is argued that the stronger a country s fiscal bureaucracy the lower its deficit ceteris paribus empirically the authors find that the state of a nation s economy heavily affects its deficit little systematic relationship is found between the ideology of the ruling political party and a nation s deficit or between the political strength of the ruling party and deficits in contrast to the findings of roubini and sachs finally it is found that the strength of a country s fiscal bureaucracy is an important influence on the deficit in these 9 industrialized parliamentary democracies

manipulable congestion tolls the recent literature on congestion pricing with large agents contains a remarkable inconsistency though agents are large enough to recognize self imposed congestion and exert market power over prices they do not take into account the impact of their own actions on the magnitude of congestion tolls when large agents are confronted with tolls derived under this parametric assumption but understand the rule used to generate them the toll system will no longer guide the market to the social optimum to address this problem the present paper derives alternate manipulable toll rules which are designed to achieve the social optimum when agents anticipate the full impact of their actions on toll liabilities

a direct test of the buffer stock model of saving recent models with liquidity constraints and impatience emphasize that consumers use savings to buffer income fluctuations when wealth is below an optimal target consumers try to increase their buffer stock of wealth by saving more when it is above target they increase consumption this important implication of the buffer stock model of saving has not been subject to direct empirical testing we derive from the model an appropriate theoretical restriction and test it using data on working age individuals drawn from the 2002 and 2004 italian surveys of household income and wealth one of the most appealing features of the survey is that it has data on the amount of wealth held for precautionary purposes which we interpret as target wealth in a buffer stock model the test results do not support buffer stock behavior even among population groups that are more likely a priori to display such behavior the saving behavior of young households is instead consistent with models in which impatience relative to prudence is not as high as in buffer stock models jel d91

intertemporal choice and consumption mobility the theory of intertemporal consumption choice makes sharp predictions about the evolution of the entire distribution of household consumption not just about its conditional mean in the paper we study the empirical transition matrix of consumption using a panel drawn from the bank of italy survey of household income and wealth we estimate the parameters that minimize the distance between the empirical and the theoretical transition matrix of the consumption distribution the transition matrix generated by our estimates matches remarkably well the empirical matrix both in the aggregate and in samples stratified by education our estimates strongly reject the consumption insurance model and suggest that households smooth income shocks to a lesser extent than implied by the permanent income hypothesis jel d52 d91 i30

the surprisingly low importance of income uncertainty for precaution abstract while it is common to use income uncertainty to explain household saving decisions there is much disagreement about the importance of precautionary saving this paper suggests that income uncertainty is not an important motive for saving although households do have other precautionary reasons to save using a question from the survey of consumer finances that asks how much households want for precautionary purposes this paper shows that expressed household preferences and liquid savings are much lower than predicted by standard modeling assumptions households rarely list unemployment as a reason to save perceived income uncertainty does not affect liquid savings or precautionary preferences neither does being in an occupation with higher income volatility instead households seem very concerned with expenditure shocks

the consumption and wealth effects of an unanticipated change in lifetime resources in 2000 italy replaced its traditional system of severance pay for public employees with a new system under the old regime severance pay was proportional to the final salary before retirement under the new regime it is proportional to lifetime earnings this reform entails substantial losses for future generations of public employees in the range of 20 000 30 000 depending on seniority using a difference in difference framework we estimate the impact of this unanticipated change in lifetime resources on the current consumption and wealth accumulation of employees affected by the reform in line with theoretical simulations we find that each euro reduction in severance pay reduces the average propensity to consume by 3 cents and increases the wealth income ratio by 0 32 the response is stronger for younger workers and for households where both spouses are public sector employees this paper was accepted by amit seru finance

network effects congestion externalities and air traffic delays or why not all delays are evil we examine two factors that explain air traffic congestion network benefits due to hubbing and congestion externalities while both factors impact congestion we find that the hubbing effect dominates empirically hub carriers incur most of the additional travel time from hubbing primarily because they cluster their flights in short time spans to provide passengers as many potential connections as possible with a minimum of waiting time non hub flights at the same hub airports operate with minimal additional travel time these results suggest that an optimal congestion tax might have a relatively small impact on flight patterns at hub airports jel l2 l5 l9 d6

fiscal policy and trade adjustment are the deficits really twins i introduction the unprecedented increase of both the fiscal and trade deficits in the united states during the 1980s led many observers to posit a causal linkage a sizable contingent of economists believe that the twin deficits concept aptly characterizes the recent relationship between federal budgetary policy and the u s trade balance in this view increased federal fiscal deficits during the 1980s were a primary cause of the massive u s trade deficits experienced as the decade unfolded however this posited causal relationship does not command universal acceptance in this paper we examine data on u s trade and federal fiscal measures along with exchange and interest rates to uncover the empirical relationship between them and to discover whether fiscal policy plays an essential role in the adjustment of the massive u s trade imbalance the twin deficits concept asserts that the deficits are twins because they are related in the following manner increased government deficits are thought to put incipient upward pressure on real interest rates this induces incipient capital in flows that lift or appreciate the real exchange value of the currency which erodes competitiveness and after a time lag results in increased trade deficits a number of recent papers examine the relationship between budget and trade deficits each contributes important insights but nothing approaching a consensus has yet emerged miller and russek 1989 find evidence of a secular relationship between the deficits under two of the three statistical techniques they employ bernheim 1988 concludes that the government deficit is a prime determinant of u s trade deficits whereas evans 1989 enders and lee 1990 and dewald and ulan 1990 find no such causal impact of fiscal deficits darrat 1988 and abell 1990 report somewhat mixed results the conflicting results in the existing literature stem from wide differences in the empirical techniques data measures and samples employed further we have found in the literature and in our work reported below that the use of differenced data versus data in level form has a major impact on the results produced and inferences drawn recent empirical literature suggests that stationarity of data is a crucial element in model specification thus the question of whether or not to difference the data should be addressed before estimation and inference classical inference about stationarity of data suffers from what sims 1988 refers to as a discontinuity in the asymptotic theory hence the classical tests used in much of the previous literature have low power to reject the null hypothesis of nonstationarity in levels bayesian inference does not suffer from this problem therefore we generate posterior probabilities using monte carlo integration that estimate probabilities that suggest whether the data are better analyzed in level or difference form despite somewhat contrasting results the classical augmented dickey fuller tests and the bayesian probability estimates both suggest that a difference specification is inappropriate we analyze empirically a five variable nonstructural vector autoregressive var model the model includes both a federal government balance and a government purchases measure to summarize fiscal policy along with these two variables and a trade balance measure we constructed real interest rate and real exchange rate variables spanning a quarterly data sample from 1961 to 1989 we estimate the model in both levels and difference form using the level specification we find strong support for the twin deficit notion that government deficits are a cause of trade deficits whereas in differences we find no such relationship furthermore the results from our monte carlo work imply that the model specified in levels is likely most appropriate for estimation and inference ii contrasting theoretical frameworks the presence of both deficits in a variant of the basic savings investment identity may provide a useful reference as in bernheim 1988 and branson 1985 for discussing the hypothesized causal relationship embodied in popular twin deficits stories 1 tdef gdef i s

do carriers internalize congestion costs empirical evidence on the internalization question abstract economists have long suggested overhauling the existing u s airport landing departure fees to reflect market valuations of scarce runway capacity economists however do not agree on the optimal congestion based pricing scheme while some researchers advocate for a uniform congestion fee regardless of a carrier s airport market share others suggest that airport tolls should only reflect the congestion costs imposed on other carriers this paper uses ten years of ontime performance data to empirically determine if carriers internalize congestion costs while previous researchers e g mayer christopher sinai todd 2003a network effects congestion externalities and air traffic delays or why all delays are not evil american economic review 93 4 1194 1215 use excess travel time to measure flight delays the contribution of this paper is the addition of on time arrival and delay measures based on actual versus scheduled arrival and departure times we find that estimates based on these new delay measures reverse earlier findings by mayer and sinai 2003a network effects congestion externalities and air traffic delays or why all delays are not evil american economic review 93 4 1194 1215 and hence imply that carriers are not internalizing flight congestion costs

government financing decisions and asset returns abstract this paper presents an empirical investigation of the relation between government financing decisions and asset returns in particular the focus is on whether a substitution of debt financing for tax financing of a given level of expenditures is associated with an increase in interest rates the paper brings a different perspective to empirical investigations of government fiscal policies by examining the response of asset prices in an efficient capital market to such policies rather than focusing on aggregate consumption behavior the results are consistent with the idea that asset prices are unrelated to how the government finances its expenditures the results however also indicate that the capital market is not indifferent with respect to the level of government expenditures as higher interest rates are associated with increases in government purchases

consumption and capital market imperfections an international comparison the excess sensitivity of consumption to current income fluctuations is higher in countries where consumers borrow less low levels of consumer debt can result either from capital market imperfections or from a low demand for loans the evidence suggests that the former view is more appropriate than the latter and thus supports the hypothesis that excess sensitivity may be attributed to liquidity constraints rather than to other factors copyright 1989 by american economic association

precautionary saving in the small and in the large the theory of precautionary saving is shown to be isomorphic to the arrow pratt theory of risk aversion making possible the application of a large body of knowledge about risk aversion to precautionary saving and more generally to the theory of optimal choice under risk in particular a measure of the strength of the precautionary saving motive analogous to the arrow pratt measure of risk aversion is used to establish a number of new propositions about precautionary saving and to give a new interpretation of the dreze modigliani substitution effect copyright 1990 by the econometric society

recursive equilibria in an aiyagari style economy with permanent income shocks in this paper we prove the existence of a recursive competitive equilibrium rce for an aiyagari style economy with permanent income shocks and perpetual youth structure we show that there exist equilibria where borrowing constraints are never binding this allows us to establish a non trivial lower bound on the equilibrium interest rate to solve the individual s problem we present a new approach that uses lattices of consumption functions to deal with the non compact state space and the unbounded utility function the approach uses only the first order conditions of the problem euler equations the proof is constructive and it serves as a theoretical foundation for the convergence of a policy function iteration procedure

economics of a bottleneck abstract drawing on vickrey amer econ rev 59 251 261 1969 and subsequent literature this paper provides a thorough economic analysis of the simplest bottleneck model of road congestion with peak load demand in the morning rush hour a fixed number of identical individuals one per car must travel from home to work between which is a bottleneck of given capacity the costs of travel include queuing time and schedule delay time early or late for work the frequency distribution of departure times adjusts so that in equilibrium all individuals have the same travel costs the paper extends the previous literature by examining a coarse toll and solving for optimal capacities the application of congestion tolls can generate efficiency gains by altering the frequency distribution of departure times previous estimates of the efficiency gains from congestion tolling are likely to be substantially downward biased because they have ignored this effect