A Poisson mixture model of discrete choice

In this paper, we introduce a new Poisson mixture model for count panel data where the underlying Poisson process intensity is determined endogenously by consumer latent utility maximization over a set of choice alternatives. This formulation accommodates the choice and count in a single random utility framework with desirable theoretical properties. Individual heterogeneity is introduced through a random coefficient scheme with a flexible semiparametric distribution. We deal with the analytical intractability of the resulting mixture by recasting the model as an embedding of infinite sequences of scaled moments of the mixing distribution, and newly derive their cumulant representations along with bounds on their rate of numerical convergence. We further develop an efficient recursive algorithm for fast evaluation of the model likelihood within a Bayesian Gibbs sampling scheme. We apply our model to a recent household panel of supermarket visit counts. We estimate the nonparametric density of three key variables of interest-price, driving distance, and their interaction-while controlling for a range of consumer demographic characteristics. We use this econometric framework to assess the opportunity cost of time and analyze the interaction between store choice, trip frequency, search intensity, and household and store characteristics. We also conduct a counterfactual welfare experiment and compute the compensating variation for a 10%-30% increase in Walmart prices.     

A household production approach to the evaluation of transportation system change

This paper intends to present a model for evaluating nationwide and interregional transportation system change from the viewpoint of the user's welfare. The model stems primarily from an adaptation of the household production approach, and thereby represents a departure from traditional methods of evaluation. In the development of our model, the transportation system changes are regarded as technical changes in the trip production function. With proper assumptions regarding the specified utility and trip production functions, it is possible to empirically evaluate the transportation system change and to measure the technical change in trip production function.     

WAS THE GOLD STANDARD REALLY DESTABILIZING?

This paper investigates the extent to which the high macroeconomic volatility experienced in the classical Gold Standard era of US history can be attributed to the monetary policy regime per se as distinct from other shocks. For this purpose, we estimate a small dynamic stochastic general equilibrium model for the classical Gold Standard era. We use this model to conduct a counterfactual experiment to assess whether a monetary policy conducted on the basis of a Taylor rule characterizing the Great Moderation data would have led to different outcomes for macroeconomic volatility and welfare in the Gold Standard era. The counterfactual Taylor rule significantly reduces inflation volatility, but at the cost of higher real‐money and interest‐rate volatility. Output volatility is very similar. The end result is no welfare improvement. Copyright © 2012 John Wiley & Sons, Ltd.     

The wages of BMI: Bayesian analysis of a skewed treatment–response model with nonparametric endogeneity

We generalize the specifications used in previous studies of the effect of body mass index (BMI) on earnings by allowing the potentially endogenous BMI variable to enter the log wage equation nonparametrically. We introduce a Bayesian posterior simulator for fitting our model that permits a nonparametric treatment of the endogenous BMI variable, flexibly accommodates skew in the BMI distribution, and whose implementation requires only Gibbs steps. Using data from the 1970 British Cohort Study, our results indicate the presence of nonlinearities in the relationships between BMI and log wages that differ across men and women, and also suggest the importance of unobserved confounding for our sample of males. Copyright © 2008 John Wiley & Sons, Ltd.     

Product Differentiation and Mergers in the Carbonated Soft Drink Industry

I simulate the competitive impact of several soft drink mergers from the 1980s on equilibrium prices and quantities. An unusual feature of soft drink demand is that, at the individual purchase level, households regularly select a variety of soft drink products. Specifically, on a given trip households may select multiple soft drink products and multiple units of each. A concern is that using a standard discrete choice model that assumes single unit purchases may understate the price elasticity of demand. To model the sophisticated choice behavior generating this multiple discreteness , I use a household-level scanner data set. Market demand is then computed by aggregating the household estimates. Combining the aggregate demand estimates with a model of static oligopoly, I then run the merger simulations. Despite moderate price increases, I find substantial welfare losses from the proposed merger between Coca-Cola and Dr. Pepper. I also find large price increases and corresponding welfare losses from the proposed merger between Pepsi and 7 UP and, more notably, between Coca-Cola and Pepsi.     

Bayesian counterfactual analysis of the sources of the great moderation

We use counterfactual experiments to investigate the sources of the large volatility reduction in US real GDP growth in the 1980s. Contrary to an existing literature that conducts counterfactual experiments based on classical estimation and point estimates, we consider Bayesian analysis that provides a straightforward measure of estimation uncertainty for the counterfactual quantity of interest. Using Blanchard and Quah's ( 1989 ) structural VAR model of output growth and the unemployment rate, we find strong statistical support for the idea that a counterfactual change in the size of structural shocks alone, with no corresponding change in the propagation of these shocks, would have produced the same overall volatility reduction as what actually occurred. Looking deeper, we find evidence that a counterfactual change in the size of aggregate supply shocks alone would have generated a larger volatility reduction than a counterfactual change in the size of aggregate demand shocks alone. We show that these results are consistent with a standard monetary VAR, for which counterfactual analysis also suggests the importance of shocks in generating the volatility reduction, but with the counterfactual change in monetary shocks alone generating a small reduction in volatility. Copyright © 2007 John Wiley & Sons, Ltd.     

Bayesian inference in a correlated random coefficients model: Modeling causal effect heterogeneity with an application to heterogeneous returns to schooling

We consider the problem of causal effect heterogeneity from a Bayesian point of view. This is accomplished by introducing a three-equation system, similar in spirit to the work of Heckman and Vytlacil (1998), describing the joint determination of a scalar outcome, an endogenous “treatment” variable, and an individual-specific causal return to that treatment. We describe a Bayesian posterior simulator for fitting this model which recovers far more than the average causal effect in the population, the object which has been the focus of most previous work. Parameter identification and generalized methods for flexibly modeling the outcome and return heterogeneity distributions are also discussed.Combining data sets from High School and Beyond (HSB) and the 1980 Census, we illustrate our methods in practice and investigate heterogeneity in returns to education. Our analysis decomposes the impact of key HSB covariates on log wages into three parts: a “direct” effect and two separate indirect effects through educational attainment and returns to education. Our results strongly suggest that the quantity of schooling attained is determined, at least in part, by the individual’s own return to education. Specifically, a one percentage point increase in the return to schooling parameter is associated with the receipt of (approximately) 0.14 more years of schooling. Furthermore, when we control for variation in returns to education across individuals, we find no difference in predicted schooling levels for men and women. However, women are predicted to attain approximately 1/4 of a year more schooling than men on average as a result of higher rates of return to investments in education.     

Incorporating activity space and trip chaining into facility siting for accessibility maximization

Location models have been widely used to support locational decisions for various service provision. One common objective of location models has been to ensure maximal accessibility of sited facilities to demand populations. Accessibility evaluation in location models often assumes that trips originate from fixed locations (usually home) and are single purpose. These assumptions contradict the empirical evidence that suggests trips also commonly originate from non-home locations and may involve multiple stops. In this study, a new multi-objective location model is developed that extents the classic p-median problem (PMP) to account for a more realistic assessment of accessibility. Based on the individual accessibility assessment, notions of trip chaining and activity space are incorporated into the model development. In addition to fixed home locations, stops along chained trips are allowed for potential service site visits, and activity space is introduced as an additional dimension to evaluate accessibility of alternative opportunities. The effectiveness of the new model is demonstrated using an application in Tucson, AZ.     

Trip Chaining: Who Wins Who Loses?

This paper studies how trip chaining (combining commuting and shopping or commuting and child care) affects market competition: in particular, pricing and the equilibrium number of firms as well as welfare. We use a monopolistic competition framework, where firms sell differentiated products as well as offering differentiated jobs to households, who are all located at some distance from the firms. The symmetric equilibriums with and without the option of trip chaining are compared. We show analytically that introducing the trip chaining option reduces the profit margin of the firms in the short run, but increases welfare. The welfare gains are, however, smaller than the transport cost savings. In the free-entry long-run equilibrium, the number of firms decreases but welfare is higher. A numerical illustration gives orders of magnitude of the different effects.     

Policy impacts on the propensity to travel by HSR in the Amsterdam – London market

This paper investigates the impacts of possible measures to enhance HSR market share in the London-Amsterdam market. To this aim, we adopted a two-level aggregate nested logit model able to jointly model trip distribution and trip generation, thus taking into account that the tested policies may increase or decrease the overall demand. The model was applied to an extensive dataset about passenger flows traveling between London airports and HSR station and Amsterdam in the period 2015–2019. The results show that both the reduction of HSR fares and the application of an air ticket tax, albeit with different impacts in terms of stimulus or reduction effect on overall demand, are ineffective in increasing HSR market share, if not adequately supported by improving HSR service. Increasing HSR frequency and reducing HSR travel times constitute the best opportunities to increase HSR ridership by stimulating a higher substitution effect than modifications in relative fares. Lastly, the recent queueing at airports, following staff shortages and strikes, significantly lower air transport demand and potentially has a substantial upward effect on HSR market share.     

Recreation Demand and Residential Location

We use the properties of competitive location equilibrium to study the demand for recreation and the choice of primary residence location. Location-specific recreation and employment lead to pooling equilibria in which consumers reside according to their preference for recreation. In general, the stronger the taste for recreation, the greater the attraction of living close to the recreation site and the lower the demand for other goods, including housing. We explore the effects of trip frequency, trip length, and recreation cost on the spatial distribution of consumers. We also consider the effect of the wage rate on recreation and location demands.     

Congestion in a city with a central bottleneck

We consider dynamic congestion in an urban setting where trip origins are spatially distributed. All travelers must pass through a downtown bottleneck in order to reach their destination in the CBD. Each traveler chooses departure time to maximize general concave scheduling utility. We find that, at equilibrium, travelers sort according to their distance to the destination; the queue is always unimodal regardless of the spatial distribution of trip origins. We construct a welfare maximizing tolling regime, which eliminates congestion. All travelers located beyond a critical distance from the CBD gain from tolling, even when toll revenues are not redistributed, while nearby travelers lose. We discuss our results in the context of acceptability of tolling policies.     

Vertical structure and the risk of rent extraction in the electricity industry

This paper studies how competition and vertical structure jointly determine generating capacities, retail prices, and welfare in the electricity industry. Analyzing a model in which demand is uncertain and retailers must commit to retail prices before they buy electricity in the wholesale market, we show that welfare is highest if competition in generation and retailing is combined with vertical separation. Vertically integrated generators choose excessively high retail prices and capacities to avoid rent extraction in the wholesale market when their retail demand exceeds their capacity. Vertical separation eliminates the risk of rent extraction and yields lower retail prices.     

A reservation-based parking behavioral model for parking demand management in urban areas

The rapid increase in car ownership has become a land-use problem in many cities which have limited land for parking. It also has adverse impacts on congestion, air quality, energy consumption, as well as losses in productivity, among other consequences. The problem worsens in some cities due to the adoption of inefficient mandatory minimum parking policies for new projects, according to a building's use and size, which incentivizes driving. Therefore, it is necessary to assess appropriate parking management policies that maximize social welfare. In this regard, this paper presents a reservation-based parking behavioral hybrid choice model for parking demand management policies in urban areas, that appropriately represents the behavior of private vehicle users when choosing their parking site. The proposed model is statistically significant and consistent with expected behavior and microeconomic theory. The results demonstrate that the possibility of reserving a parking space has a significant impact on car parking market share on- and off-street. The three latent variables included in the model (pro-parking attitude, perception of risk for parking on- and off-street) have a significant effect on the modal split and the evaluation of appropriate parking policies that consider heterogeneity. The latent variable that most impacts the modal shift is the pro-parking attitude, which can generate up to 7% change in the modal partition.     

Inference on impulse response functions in structural VAR models

Skepticism toward traditional identifying assumptions based on exclusion restrictions has led to a surge in the use of structural VAR models in which structural shocks are identified by restricting the sign of the responses of selected macroeconomic aggregates to these shocks. Researchers commonly report the vector of pointwise posterior medians of the impulse responses as a measure of central tendency of the estimated response functions, along with pointwise 68% posterior error bands. It can be shown that this approach cannot be used to characterize the central tendency of the structural impulse response functions. We propose an alternative method of summarizing the evidence from sign-identified VAR models designed to enhance their practical usefulness. Our objective is to characterize the most likely admissible model(s) within the set of structural VAR models that satisfy the sign restrictions. We show how the set of most likely structural response functions can be computed from the posterior mode of the joint distribution of admissible models both in the fully identified and in the partially identified case, and we propose a highest-posterior density credible set that characterizes the joint uncertainty about this set. Our approach can also be used to resolve the long-standing problem of how to conduct joint inference on sets of structural impulse response functions in exactly identified VAR models. We illustrate the differences between our approach and the traditional approach for the analysis of the effects of monetary policy shocks and of the effects of oil demand and oil supply shocks.     

Efficiency loss in a Cournot oligopoly with convex market demand

We consider a Cournot oligopoly model where multiple suppliers (oligopolists) compete by choosing quantities. We compare the social welfare achieved at a Cournot equilibrium to the maximum possible, for the case where the inverse market demand function is convex. We establish a lower bound on the efficiency of Cournot equilibria in terms of a scalar parameter derived from the inverse demand function, namely, the ratio of the slope of the inverse demand function at the Cournot equilibrium to the average slope of the inverse demand function between the Cournot equilibrium and a social optimum. Also, for the case of a single, monopolistic, profit maximizing supplier, or of multiple suppliers who collude to maximize their total profit, we establish a similar but tighter lower bound on the efficiency of the resulting output. Our results provide nontrivial quantitative bounds on the loss of social welfare for several convex inverse demand functions that appear in the economics literature.     

Labor force participation and pair-wise efficient contracts with search and bargaining

A “constant” wage is pair-wise inefficient in a standard search model when workers endogenously separate from employment. We derive a pair-wise efficient employment contract that involves workers paying a hiring fee (or bond) upon the formation of a match. We estimate the constant wage and pair-wise efficient contract assuming the hiring fee is unobservable, and find evidence to reject the pair-wise efficient contract in favor of the constant wage rule. A counterfactual experiment reveals the current level of labor force participation to be 9.6% below the efficient level, and a structural shift to the pair-wise efficient contract improves welfare by roughly 3.5%.     

A dynamic almost ideal demand system incorporating consumer expectations

In this paper a theoretical framework is presented for the analysis of the effects of psychological, perceptual or expectational factors on household expenditure within a complete demand system. The model was estimated using the Consumer Sentiment Index, which represents an index of consumer perceptions of economic conditions. Evidence was found for significant expectational effects on five of nine expenditure categories—food at home, alcohol, housing, durables and other services. The direct expectation effects were found to be small in size. The results demonstrate the model's potential usefulness as a framework for modelling consumer behavioral responses to expectations and for evaluating the welfare implications of policy-induced changes in expectations.