Quality-Adjusted Prices of Japanese Mobile Phone Handsets and Carriers’ Strategies

In order to discuss oligopolists’ strategic determination of quality-adjusted prices (QAPs), we conducted a hedonic regression analysis using adjacent periods and estimated the QAPs of mobile phone handsets sold in Japan between 2002 and mid-2007 for each carrier. We observed (1) a decreasing trend in QAP for each carrier, (2) a more rapid decrease in the QAPs of the two smaller carriers’ handsets relative to that of the largest carrier, and (3) a turnover cycle of the QAPs between the two smaller carriers. If both small carriers decrease their QAPs at roughly the same time, neither will significantly increase their subscriber share, which can generate a turnover cycle of QAPs.     

Inequality and public debt: A positive analysis

This study extends the multi‐country, politico‐economic model of fiscal policy to incorporate wage inequality within each country. In this extended framework, we present conflict over fiscal policy within and across generations and show that a low‐inequality country realizes tight fiscal policy with low public debt accumulation, whereas a high‐inequality country experiences loose fiscal policy with high public debt. This model prediction is consistent with empirical evidence from OECD countries for the years 1980 to 2010.     

Misspecification in Dynamic Panel Data Models and Model‐Free Inferences

This paper discusses the issue of model misspecification and model‐free methods in dynamic panel data analysis. We primarily review existing results, but also provide several new results. When the dynamics are homogeneous, we show that several widely used estimators for panel first‐order autoregressive AR(1) models converge to first‐order autocorrelation, even under misspecification. Under heterogeneity, these estimators converge to the ratio of the means of the first‐order autocovariances and variances. We also discuss the estimation of autocovariances, the estimation of panel AR(∞) models, and the estimation of the distribution of the heterogeneous mean and autocovariances.     

Old‐age Social Security versus Forward Intergenerational Public Goods Provision

This paper introduces an overlapping‐generations model with earnings heterogeneity and borrowing constraints. The labour income tax and the allocation of tax revenue between social security and forward intergenerational public goods are determined in a bidimensional majoritarian voting game played by successive generations. The political equilibrium is characterized by an ends‐against‐the‐middle equilibrium where low‐income and high‐income individuals form a coalition in favour of a lower tax rate and less social security while middle‐income individuals favour a higher tax rate and greater social security. Government spending then shifts from social security to public goods provision if higher wage inequality is associated with a borrowing constraint and a high elasticity of marginal utility of youth consumption.     

Doubly robust uniform confidence band for the conditional average treatment effect function

In this paper, we propose a doubly robust method to estimate the heterogeneity of the average treatment effect with respect to observed covariates of interest. We consider a situation where a large number of covariates are needed for identifying the average treatment effect but the covariates of interest for analyzing heterogeneity are of much lower dimension. Our proposed estimator is doubly robust and avoids the curse of dimensionality. We propose a uniform confidence band that is easy to compute, and we illustrate its usefulness via Monte Carlo experiments and an application to the effects of smoking on birth weights.     

Wants and past knowledge: Growth cycles with emerging industries

This paper develops a theory of endogenous growth cycles focusing on the interaction between consumers' desire to satisfy an indefinite range of wants and firms' incentive to utilize knowledge from past production experiences. We show that firms endogenously form a number of distinguishable industries as accumulated knowledge induces them to agglomerate in the technology space. Knowledge accumulation in existing industries reduces production costs, but, as the diminishing returns from learning sets in, some firms start to adopt previously unexplored technologies so that their new goods fit consumers' unsatisfied wants and attract large demand. Thus, sporadic emergence of new industries generates growth cycles, where both the timing and the new technology to be adopted are endogenously determined. New industries based on new technology reduce the rate of per capita GDP growth in the initial phase, but nonetheless are indispensable for sustained economic growth in the long run.     

Hahn-Hausman test as a specification test

This paper develops a modified version of the Sargan [Sargan, J.D., 1958. The estimation of economic relationships using instrumental variables. Econometrica 26 (3), 393-415] restrictions, and shows that it is numerically equivalent to the test statistic of Hahn and Hausman [Hahn, J., Hausman, J., 2002. A new specification test for the validity of instrumental variables. Econometrica 70 (1), 163-189] up to a sign. The modified Sargan test is constructed such that its asymptotic distribution under the null hypothesis of correct specification is standard normal when the number of instruments increases with the sample size. The equivalence result is useful in understanding what the Hahn-Hausman test detects and its power properties.     

Dynamics,stability, and foresight in the Shapley–Scarf housing market

While most of the literature starting with Shapley and Scarf (1974) have considered a static exchange economy with indivisibilities, this paper studies the dynamics of such an economy. We find that both the dynamics generated by competitive equilibrium and the one generated by the weak dominance relation, converge to a set of allocations we define as strictly stable, which we can show to exist. Moreover, we show that even when only pairwise exchanges between two traders are allowed, the strictly stable allocations are attained eventually if traders are sufficiently farsighted.     

The relationship between arbitrage in futures and spot markets and Bitcoin price movements: Evidence from the Bitcoin markets

We examine how investors arbitrage the Bitcoin spot and futures markets. Using intraday data of the Chicago Board Options Exchange, we reconstruct the actual arbitrage condition that investors confront. We find that there are few arbitrage profit opportunities in “normal” markets, but large arbitrage profit opportunities arise during Bitcoin market “crashes.”     

Dynamic control of rural–urban migration

This study investigates the optimal urbanization control of an underdeveloped economy by specifying a simple dynamic rural–urban model in which the urban sector bears both an intertemporal positive externality and a simultaneous negative externality. The dynamic optimization problem is solved for the political intervention of the central government in an intersectoral population distribution with taxes and subsidies. Our analysis provides the following results: (i) a big-push policy that leads an economy to a higher-income steady state with urbanization is not necessarily desirable if the government cannot borrow money at a sufficiently low interest rate; (ii) in order to sustain an appropriate urbanization speed, urbanization control policy should have a switch: the urban sector should be subsidized in order to accelerate rural–urban migration in early stages of development, and taxed to decelerate and eventually cease the migration in later stages.