Why labor income shares seem to be constant?

The common assumptions that labor income share does not change over time or across countries and that factor income shares are equal to the elasticity of output with respect to factors have had important implications for economic theory. However, there are various theoretical reasons why the elasticity of output with respect to reproducible factors should be correlated with the stage of development. In particular, the behavior of international trade and capital flows and the existence of factor saving innovations imply such a correlation. If this correlation exists and if factor income shares are equal to the elasticity of output with respect to factors then the labor income share must be negatively correlated with the stage of development. We propose an explanation for why labor income share has no correlation with income per capita: the existence of a labor intensive sector which produces non tradable goods.

An empirical note on factor shares

In this study, we propose an explanation for why labor and capital shares do not seem to have a trend: an increasing trend in physical capital share is compensated by a decreasing trend in land share. Similarly, an increasing trend in human capital share is compensated by a decreasing trend in raw labor share. We also find empirical support for the claim that the elasticity of output with respect to reproducible factors, human and physical capital, is positively correlated with the income level. This result has important implications for economic growth theory and for empirical exercises related to economic growth

Biased technological change, human capital and factor shares

We propose a one-good model where technological change is factor saving and costly. We consider a production function with two reproducible factors: physical capital and human capital, and one not reproducible factor. The main predictions of the model are the following: (a) The elasticity of output with respect to the reproducible factors depends on the factor abundance of the economies. (b) The income share of reproducible factors increases with the stage of development. (c) Depending on the initial conditions, in some economies the production function converges to AK, while in other economies long-run growth is zero. (d) The share of human factors (raw labor and human capital) converges to a positive number lower than one. Along the transition it may decrease, increase or remain constant.

Dynamic programming for stochastic target problems, Viscosity solutions and hedging in markets with Portfolio constraints and large investors

The purpose of this expository arti le is to present a self- ontained overview of some results on the hara terization of the optimal value fun tion of a sto hasti target problem as (dis ontinuous) vis osity solution of a ertain dynami programming PDE and its appli ation to the problem of hedging ontingent laims in the presen e of portfolio onstraints and large investors

Evidence of induced innovation in US Sectoral Capital’s Shares

We use annual data on capital’s share and relative factor prices from 35 US industries from 1960 to 2005 to test the induced innovation hypothesis. We derive, from a production function framework, testable implications for the effect of contemporaneous and lagged factor price ratios on capital’s share of production. The predicted effect is positive or negative depending on the elasticity of substitution between labor and capital. From panel regressions, the estimated effect of the contemporaneous factor price ratio implies an elasticity of substitution that is less than unity, consistent with the consensus from the literature. Based on this, our negative estimated effects for lagged price ratios are both statistically significant and consistent with the induced innovation hypothesis.

Factor saving innovations and factor income shares

We present an endogenous growth model where innovations are factor saving. Technologies can be changed paying a cost and technological change takes place only if the benefits are larger than the costs. Since the gains derived from factor saving innovations depend on factor abundance, biased innovations respond to changes in factors supply. Therefore, as an economy becomes more capital abundant agents try to use capital more intensively. Consequently, (a) the elasticity of output with respect to reproducible factors depends on the capital abundance of the economy and (b) the income share of reproducible factors increases as the economy grows. Another insight of the model is that in some economies the production function converges to an AK in the long run, while in others long-run growth is zero

Factor shares at the sector level, Colombia 1990-2005

In general, empirical studies on economics rely on the assumption of constant capital share of income both at the aggregate level and at the sector level. However, there is no empirical evidence supporting the constancy of capital share at the sector level. In this paper, using Colombian data, we measure capital share for 48 sectors during the period 1990-2005. We also explore the relation between capital's share and factor prices and the behavior of capital share during the business cycle. The main results are the following: (i) capital share is not constant but, rather, has an increasing trend; (ii) capital shares growth rates positively correlate with sector value-added growth; (iii) the capital shares behave pro-cyclically; and (iv) there is a positive correlation between capital shares and real wages and a negative correlation between capital shares and interest rates. These results suggest that the usual assumption of constant factor shares is not accurate.

If factor shares are not constant then we have a measurment problem. can we solve it?

Recent evidence show that factor shares, if properly measured, are far from constant. Moreover, the shares of natural resources and raw labor seem to be negatively correlated with income per capita while the share of human and physical capital is positively correlated with income per capita. Now, if factor shares are not constant then (i) growth accounting exercises rely on a false assumption and (ii) there is a measurement problem. The effect that change s in factor shares ha ve on output depend on the relative abundance of factors and, fo r this reason, it is necessary to have correct measures. We propose an empiri cal methodology to solve the measurement issue and estimate TFP growth.

Confidence sets for asset correlations in portfolio credit risk

Asset correlations are of critical importance in quantifying portfolio credit risk and economic capitalin financial institutions. Estimation of asset correlation with rating transition data has focusedon the point estimation of the correlation without giving any consideration to the uncertaintyaround these point estimates. In this article we use Bayesian methods to estimate a dynamicfactor model for default risk using rating data (McNeil et al., 2005; McNeil and Wendin, 2007).Bayesian methods allow us to formally incorporate human judgement in the estimation of assetcorrelation, through the prior distribution and fully characterize a confidence set for the correlations.Results indicate: i) a two factor model rather than the one factor model, as proposed bythe Basel II framework, better represents the historical default data. ii) importance of unobservedfactors in this type of models is reinforced and point out that the levels of the implied asset correlationscritically depend on the latent state variable used to capture the dynamics of default,as well as other assumptions on the statistical model. iii) the posterior distributions of the assetcorrelations show that the Basel recommended bounds, for this parameter, undermine the levelof systemic risk.

Mis lenguas, mis joyas : el Portfolio europeo de las lenguas, un instrumento para fomentar el respeto a la diversidad lingüística y cultural.

Resumen basado en el de la publicación. Resumen en inglés. Monográfico: Las lenguas del mundo

El portfolio escolar.

Resumen tomado de la publicación. Suplemento El Portfolio escolar, n. 2

¿A qué viene esto del Portfolio?

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El portfolio escolar.

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El portfolio escolar.

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El portfolio escolar.

Resumen tomado de la publicación. Suplemento El portfolio escolar, n. 5