Selahattin Imrohoroglu

Stock returns and volatility in emerging financial markets

In this paper we study the dynamic behavior of stock returns and volatility in emerging financial markets. In particular, we focus our attention on the following questions: (1) Does stock return volatility in emerging markets change over time? If so, are volatility changes predictable? (2) How frequent are big surprises in emerging stock markets? (3) Is there any relationship between market risk and expected returns? (4) Has liberalization affected return volatility in emerging financial markets? ; Our findings can be summarized as follows. First, there is strong evidence of predictable time-varying volatility in almost all countries. In general, changes in volatility are highly persistent. Second, a fat-tailed distribution improves the fitting ability of the model. Third, investors are not rewarded for market-wide risk. Finally, we do not find any systematic effect of liberalization on stock market volatility.

A life cycle analysis of social security

SummaryWe develop an applied general equilibrium model to examine the optimal social security replacement rate and the welfare benefits associated with it. Our setup consists of overlapping generations of 65-period lived individuals facing mortality risk and individual income risk. Private credit markets, including markets for private annuities, are closed by assumption. Unlike previous analyses, we find that an unfunded social security system may well enhance economic welfare. In our benchmark economy, the optimal social security replacement rate is 30%, and an empirically more plausible replacement rate of 60% raises welfare compared with an economy with no social security system.

Time-Inconsistent Preferences and Social Security

In this paper we examine the role of social security in an economy populated by overlapping generations of individuals with time-inconsistent preferences who face mortality risk, individual income risk, and borrowing constraints. Agents in this economy are heterogeneous with respect to age, employment status, retirement status, hours worked, and asset holdings. We consider two cases of time-inconsistent preferences. First, we model agents as quasi-hyperbolic discounters. They can be sophisticated and play a symmetric Nash game against their future selves; or they can be naive and believe that their future selves will exponentially discount. Second, we consider retrospective time inconsistency. We find that (1) there are substantial welfare costs to quasi-hyperbolic discounters of their time-inconsistent behavior, (2) social security is a poor substitute for a perfect commitment technology in maintaining old-age consumption, (3) there is little scope for social security in a world of quasi-hyperbolic discounters (with a short-term discount rate up to 15%), and, (4) the ex ante annual discount rate must be at least 10% greater than seems warranted ex post in order for a majority of individuals with retrospective time inconsistency to prefer a social security tax rate of 10% to no social security. Our findings question the effectiveness of unfunded social security in correcting for the undersaving resulting from time-inconsistent preferences.

A Quantitative Analysis of Capital Income Taxation

This paper studies the quantitative impact of eliminating capital income taxation on capital accumulation and steady-state welfare in a general equilibrium model with overlapping generations of sixty-five-period-lived individuals who face idiosyncratic earnings risk, borrowing constraints, and life-span uncertainty. Under a wide range of parameter configurations, the capital income tax rate that maximizes steady-state welfare is positive, even though eliminating it completely would raise the steady-state capital stock toward the Golden Rule. This is because the tax burden is shifted toward the younger and liquidity constrained years, reducing the individuals ability to self-insure. Copyright 1998 by Economics Department of the University of Pennsylvania and the Osaka University Institute of Social and Economic Research Association.

GMM Estimates of Currency Substitution between the Canadian Dollar and the U.S. Dollar

This paper investigates the empirical strength of currency substitution between the Canadian dollar and the U.S. dollar. Euler equations implied by a small, open economy, money-in-the-utility-function model are estimated and tested by Hansens generalized method of moments procedure. The major empirical finding is that both the elasticity of currency substitution and the share of U.S. currency in the production of Canadian liquidity services are economically small even though the combined domestic and U.S. real balances appear to provide statistically significant economizing on transactions costs. Copyright 1994 by Ohio State University Press.

Growth and welfare analysis of tax progressivity in a heterogeneous-agent model

In this paper, we use a general equilibrium model of endogenous growth in which there is heterogeneity in skill, income, and tax rates to evaluate the effect of progressivity of taxes on growth and welfare. In this framework, changes in the progressivity of tax rates can have positive growth effects even in situations where changes in flat rate taxes have no effect. Experiments on a calibrated model indicate that the quantitative effects of moving to a flat rate system are economically significant. The assumption made about the engine of growth - an external effect arising from production activities of skilled workers or intentional employment of skilled workers for research and other productivity enhancing activities - has an important effect on the impact of a change in progressivity. Welfare is unambiguously higher in a flat rate system when comparisons are made across balanced growth equilibria; however, when the costs of transition to the higher growth equilibrium are taken into account, only the currently skilled slightly prefer the flat system. (Copyright: Elsevier)

AGRICULTURAL PRODUCTIVITY AND GROWTH IN TURKEY

This paper investigates the growth experience of one country in detail in order to enhance our understanding of important factors that affect economic growth. Using a two-sector model, we identify low productivity growth in the agricultural sector as the main reason for the divergence of income per capita between Turkey and its peer countries between 1968 and 2005. An extended model that incorporates distortions in the use of intermediate goods in producing agricultural output indicates that policies that have different effects across sectors and across time may be important in explaining the growth experience of countries.

A Numerical Algorithm for Solving Models With Incomplete Markets

We describe an incomplete markets model and outline a numerical solution algorithm to compute its steady- state equilibrium. The model departs from the Arrow- Debreu world of complete contingent claims markets by assuming the presence of borrowing constraints. Solution methods that rely on approximations around some reference point or those that use the Euler equa tions in an interior solution are not suitable for the present model. Rather, we outline a numerical solution algorithm that discretizes the state space and the deci sion space and iterates on a numerical procedure that obtains the decision rules and distributions of agent types for all cohorts in an attempt to find the steady- state equilibrium of the model. The algorithm is imple mented using the Fortran compilers on the Minnesota CRAY X-MP and San Diego CRAY Y-MP/8-864.

Can Guest Workers Solve Japan's Fiscal Problems?

The labor force in Japan is projected to fall from about 64 million in 2014 to nearly 20 million in 2100. In addition, large increases in aging related public expenditures are projected which would require unprecedented fiscal adjustments to achieve sustainability under current policies. In this paper, we develop an overlapping generations model calibrated to micro and macro data in Japan and conduct experiments with a variety of guest worker and immigration programs under different assumptions on factor prices and labor productivities. Against a baseline general equilibrium transition which relies on a consumption tax to achieve fiscal sustainability, we compute alternative transitions with guest worker programs that bring in annual flows of foreign born workers residing in Japan for 10 years with the share of guest workers in total employment in a range between 4% and 16%. Depending on the size and skill distribution of guest workers, these programs significantly mitigate Japans fiscal imbalance problem with a relatively manageable and temporary increase in the consumption tax rate.

A Markov switching model for the Hungarian price stabilization plan of 1924

Abstract This paper compares the goodness of fit of a linear ar(1) model and a Markov ar(1) alternative using data on the inflation rate during the Hungarian hyperinflation (August 1921–March 1924) and stabilization (March 1924–November 1926) periods. First, in-sample forecasting measures (RMSE and MAPE) indicate that the Markov ar(1) uniformly dominates the linear ar(1) for horizons of one to ten periods. Second, bootstrapped samples yield a likelihood ratio test statistic which easily rejects the linear ar(1) in favor of the Markov ar(1) alternative.