Susumu Imai

Biography

Susumu Imai joined the Economics Discipline Group in January 2013. He has received his PhD in economics from the University of Minnesota in 1998 and has held an academic position at the Pennsylvania State University, Concordia University and Queen's University.
Please visit his personal website.

Associate Professor, Economics Discipline Group
Philosophy/Economics
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Phone
+61 2 9514 7720
Room
CB05D.03.22A

Research Interests

Empirical Labor Economics, Empirical Industrial Organization, Empirical Trade, Bayesian Econometrics.

Can supervise: Yes

Journal Articles

Imai, S., Katayama, H. & Krishna, K. 2013, 'A quantile-based test of protection for sale model', Journal of International Economics, vol. 91, no. 1, pp. 40-52.
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This paper proposes a new test of the Protection for Sale (PFS) model by Grossman and Helpman (1994). Unlike existing methods in the literature, our approach does not require any data on political organization. We use quantile and IV quantile regressions in our tests, using the data from Gawande and Bandyopadhyay (2000). Surprisingly, the results do not provide any evidence favoring the PFS model. We also explain why previous work may have found support for it.
Ching, A., Imai, S., Ishihara, M. & Jain, N. 2012, 'A practitioner's guide to Bayesian estimation of discrete choice dynamic programming models', Quantitative Marketing and Economics, vol. 10, no. 2, pp. 151-196.
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This paper provides a step-by-step guide to estimating infinite horizon discrete choice dynamic programming (DDP) models using a new Bayesian estimation algorithm (Imai et al., Econometrica 77:1865+1899, 2009a) (IJC). In the conventional nested fixed point algorithm, most of the information obtained in the past iterations remains unused in the current iteration. In contrast, the IJC algorithm extensively uses the computational results obtained from the past iterations to help solve the DDP model at the current iterated parameter values. Consequently, it has the potential to significantly alleviate the computational burden of estimating DDP models. To illustrate this new estimation method, we use a simple dynamic store choice model where stores offer +frequent-buyer+ type rewards programs. Our Monte Carlo results demonstrate that the IJC method is able to recover the true parameter values of this model quite precisely. We also show that the IJC method could reduce the estimation time significantly when estimating DDP models with unobserved heterogeneity, especially when the discount factor is close to 1.
Imai, S., Jain, N. & Ching, A. 2009, 'Bayesian estimation of dynamic discrete choice models', Econometrica, vol. 77, no. 6, pp. 1865-1899.
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We propose a new methodology for structural estimation of infinite horizon dynamic discrete choice models. We combine the dynamic programming (DP) solution algorithm with the Bayesian Markov chain Monte Carlo algorithm into a single algorithm that solves the DP problem and estimates the parameters simultaneously. As a result, the computational burden of estimating a dynamic model becomes comparable to that of a static model. Another feature of our algorithm is that even though the number of grid points on the state variable is small per solution-estimation iteration, the number of effective grid points increases with the number of estimation iterations. This is how we help ease the +curse of dimensionality.+ We simulate and estimate several versions of a simple model of entry and exit to illustrate our methodology. We also prove that under standard conditions, the parameters converge in probability to the true posterior distribution, regardless of the starting values.
Imai, S., Katayama, H. & Krishna, K. 2009, 'Protection for sale or surge protection?', European Economic Review, vol. 53, no. 6, pp. 675-688.
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This paper asks whether the results obtained from using the standard approach to testing the influential Grossman and Helpman +protection for sale+ model of political economy might arise from a simpler setting. A model of imports and quotas with protection occurring in response to import surges, but only for organized industries, is simulated and shown to provide parameter estimates consistent with the protection for sale framework. This suggests that the standard approach may be less of a test than previously thought.
Imai, S., Katayama, H. & Krishna, K. 2009, 'Is Protection Really for Sale? A Survey and Directions for Future Research', International Review of Economics and Finance, vol. 18, no. 2, pp. 181-191.
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This paper critically and selectively surveys the literature on protection for sale and discusses directions for future research in this area. It suggests that the standard approach needs to be augmented to provide more compelling tests of this model.
Imai, S. & Keane, M. 2004, 'Intertemporal Labor Supply and Human Capital Accumulation', International Economic Review, vol. 45, no. 2, pp. 601-641.
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We solve and estimate a dynamic model that allows agents to optimally choose their labor hours and consumption and that allows for both human capital accumulation and savings. Estimation results and simulation exercises indicate that the intertemporal elasticity of substitution is much higher than the conventional estimates and the downward bias comes from the omission of the human capital accumulation effect. The human capital accumulation effect renders the life-cycle path of the shadow wage relatively flat, even though wages increase with age. Hence, a rather flat life-cycle labor supply path can be reconciled with a high intertemporal elasticity of substitution.
Imai, S. & Krishna, K. 2004, 'Employment, deterrence, and crime in a dynamic model', International Economic Review, vol. 45, no. 3, pp. 845-872.
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Erdem, T., Imai, S. & Keane, M. 2003, 'Brand and quantity choice dynamics under price uncertainty', Quantitative Marketing and Economics, vol. 1, no. 1, pp. 5-64.