Information technology and productivity: where are we now and where are we going?

Productivity growth in the U.S. economy jumped during the second half of the 1990s, a resurgence that many analysts linked to developments in information technology (IT). However, shortly after this consensus emerged, demand for IT products fell sharply, leading to a debate about the connection between IT and productivity and about the sustainability of the faster growth. ; This article contributes to this debate in two ways. First, the authors provide updated estimates of the proximate sources of growth using a growth accounting framework that focuses on information technology. Their results confirm that the acceleration in labor productivity after 1995 was driven by the greater use of IT capital goods and the more rapid efficiency gains in the production of these goods. Second, to assess whether the pickup in productivity growth is sustainable, the authors analyze the steady-state properties of a multisector growth model. This exercise generates a range for labor productivity growth of 2 percent to 2 3/4 percent per year, which suggests that much-and possibly all-of the resurgence is sustainable. ; The analysis also highlights that future increases in output will depend on the pace of technological advance in the semiconductor industry and on the extent to which products embodying these advances diffuse through the economy.Information technology ; Productivity ; Technology ; Economic development

Les technologies de l’information et la productivité : situation actuelle et perspectives d’avenir

Dans la deuxième moitié des années quatre-vingt-dix, la croissance de la productivité de l’économie américaine a rebondi, un phénomène que nombre d’analystes ont attribué aux technologies de l’information. Cependant, peu de temps après que ce consensus se soit imposé, la demande pour les produits de technologies de l’information s’effondrait, relançant un vif débat sur le lien entre les technologies de l’information et la productivité, de même que sur la durabilité éventuelle d’une croissance aussi forte. Nous apportons notre contribution à ce débat de deux manières : premièrement, dans le but d’évaluer la robustesse de notre argumentation antérieure, nous prolongerons, jusqu’à la fin de 2001, notre analyse de la comptabilité de la croissance, dont nous avons déjà publié les résultats (Oliner et Sichel, 2000a). Les nouveaux résultats confirment les conclusions de nos travaux antérieurs : la croissance accélérée de la productivité du travail après 1995 découle principalement de l’usage croissant des biens d’équipement de type technologies de l’information et de gains d’efficacité accrus du côté de leur production ; deuxièmement, nous analyserons les propriétés de régime d’état stationnaire d’un modèle de croissance multisectoriel, afin de jauger la durabilité potentielle d’un tel regain de productivité. Nous en déduirons une fourchette de valeurs pour la croissance de la productivité du travail, se situant entre 2 % et 2 ¾ % par année, ce qui laisse présager que l’essentiel – sinon la totalité – de ce regain de vitalité pourrait être durable.Productivity growth in the U.S. economy jumped during the second half of the 1990s, a resurgence that many analysts linked to information technology (IT). However, shortly after this consensus emerged, demand for IT products fell sharply, leading to a lively debate about the connection between IT and productivity and about the sustainability of the faster growth. We contribute to this debate in two ways. First, to assess the robustness of the earlier evidence, we extend the growth-accounting results in Oliner and Sichel (2000a) through 2001. The new results confirm the basic story in our earlier work – that the acceleration in labor productivity after 1995 was driven largely by the greater use of IT capital goods and by the more rapid efficiency gains in the production of IT goods. Second, to assess whether the pickup in productivity growth is sustainable, we analyze the steady-state properties of a multi-sector growth model. This exercise generates a range for labor productivity growth of 2 percent to 2 ¾ percent per year, which suggests that much – and possibly all – of the resurgence is sustainable

How Fast Do Personal Computers Depreciate? Concepts and New Estimates

This paper provides new estimates of depreciation rates for personal computers using an extensive database of prices of used PCs. Our results show that PCs lose roughly half their remaining value, on average, with each additional year of use. We decompose that decline into age-related depreciation and a revaluation effect, where the latter effect is driven by the steep ongoing drop in the constant-quality prices of newly-introduced PCs. Our results are directly applicable for measuring the depreciation of PCs in the National Income and Product Accounts (NIPAs) and were incorporated into the December 2003 comprehensive NIPA revision. Regarding tax policy, our estimates suggest that the current tax depreciation schedule for PCs closely tracks the actual loss of value in a zero-inflation environment. However, because the tax code is not indexed for inflation, the tax allowances would be too small in present value for inflation rates above the very low level now prevailing.

Is the Information Technology Revolution Over?

Given the slowdown in labor productivity growth in the mid-2000s, some have argued that the boost to labor productivity from IT may have run its course. This paper contributes three types of evidence to this debate. First, we show that since 2004, IT has continued to make a significant contribution to labor productivity growth in the United States, though it is no longer providing the boost it did during the productivity resurgence from 1995 to 2004. Second, we present evidence that semiconductor technology, a key ingredient of the IT revolution, has continued to advance at a rapid pace and that the BLS price index for microprocesssors may have substantially understated the rate of decline in prices in recent years. Finally, we develop projections of growth in trend labor productivity in the nonfarm business sector. The baseline projection of about 1.75 percent a year is better than recent history but is still below the long-run average of 2.25 percent. However, we see a reasonable prospect – particularly given the ongoing advance in semiconductors – that the pace of labor productivity growth could rise back up to or exceed the long-run average. While the evidence is far from conclusive, we judge that "No, the IT revolution is not over.

Explaining a Productive Decade

This paper analyzes the sources of recent U.S. productivity growth using both aggregate and industry-level data. The paper confirms the central role of information technology in the productivity revival during 1995-2000 and shows that it played a significant, although smaller, role after 2000. Productivity growth after 2000 appears to have been boosted by industry restructuring and cost cutting in response to profit pressures, an unlikely source of future strength. In addition, the incorporation of intangible capital into the growth accounting framework somewhat diminishes estimates of labor productivity's performance since 2000 and makes the gain during 1995-2000 look larger than in the official data. Finally, the paper examines the outlook for trend growth in labor productivity; the resulting estimate, which is subject to much uncertainty, is centered at 2 1/4 percent a year, faster than the lackluster pace that prevailed before 1995 but somewhat slower than the 1995-2000 average.macroeconomics, productivity growth, labor productivity

Spreading lengths of Hermite polynomials

The Renyi, Shannon and Fisher spreading lengths of the classical or hypergeometric orthogonal polynomials, which are quantifiers of their distribution all over the orthogonality interval, are defined and investigated. These information-theoretic measures of the associated Rakhmanov probability density, which are direct measures of the polynomial spreading in the sense of having the same units as the variable, share interesting properties: invariance under translations and reflections, linear scaling and vanishing in the limit that the variable tends towards a given definite value. The expressions of the Renyi and Fisher lengths for the Hermite polynomials are computed in terms of the polynomial degree. The combinatorial multivariable Bell polynomials, which are shown to characterize the finite power of an arbitrary polynomial, play a relevant role for the computation of these information-theoretic lengths. Indeed these polynomials allow us to design an error-free computing approach for the entropic moments (weighted L^q-norms) of Hermite polynomials and subsequently for the Renyi and Tsallis entropies, as well as for the Renyi spreading lengths. Sharp bounds for the Shannon length of these polynomials are also given by means of an information-theoretic-based optimization procedure. Moreover, it is computationally proved the existence of a linear correlation between the Shannon length (as well as the second-order Renyi length) and the standard deviation. Finally, the application to the most popular quantum-mechanical prototype system, the harmonic oscillator, is discussed and some relevant asymptotical open issues related to the entropic moments mentioned previously are posed.Comment: 16 pages, 4 figures. Journal of Computational and Applied Mathematics (2009), doi:10.1016/j.cam.2009.09.04

Fluid-assisted grain size reduction leads to strain localization in oceanic transform faults

Oceanic Transform Faults are major plate boundaries representing the most seismogenic part of the mid ocean ridge system. Nonetheless, their structure and deformation mechanisms at depth are largely unknown due to rare exposures of deep sections. Here we study the mineral fabric of deformed mantle peridotites - ultramafic mylonites - collected from the transpressive Atobá ridge, along the northern fault of the St. Paul transform system in the Equatorial Atlantic Ocean. We show that, at pressure and temperature conditions of the lower oceanic lithosphere, the dominant deformation mechanism is fluid-assisted dissolution-precipitation creep. Grain size reduction during deformation is enhanced by dissolution of coarser pyroxene grains in presence of fluid and contextual precipitation of small interstitial ones, leading to strain localization at lower stresses than dislocation creep. This mechanism potentially represents the dominant weakening factor in the oceanic lithosphere and a main driver for the onset and maintenance of oceanic transform faults

Quantifying the effects of hydrogen on carbon assimilation in a seafloor microbial community associated with ultramafic rocks

Thermodynamic models predict that H2 is energetically favorable for seafloor microbial life, but how H2 affects anabolic processes in seafloor-associated communities is poorly understood. Here, we used quantitative 13C DNA stable isotope probing (qSIP) to quantify the effect of H2 on carbon assimilation by microbial taxa synthesizing 13C-labeled DNA that are associated with partially serpentinized peridotite rocks from the equatorial Mid-Atlantic Ridge. The rock-hosted seafloor community was an order of magnitude more diverse compared to the seawater community directly above the rocks. With added H2, peridotite-associated taxa increased assimilation of 13C-bicarbonate and 13C-acetate into 16S rRNA genes of operational taxonomic units by 146% (±29%) and 55% (±34%), respectively, which correlated with enrichment of H2-oxidizing NiFe-hydrogenases encoded in peridotite-associated metagenomes. The effect of H2 on anabolism was phylogenetically organized, with taxa affiliated with Atribacteria, Nitrospira, and Thaumarchaeota exhibiting the most significant increases in 13C-substrate assimilation in the presence of H2. In SIP incubations with added H2, an order of magnitude higher number of peridotite rock-associated taxa assimilated 13C-bicarbonate, 13C-acetate, and 13C-formate compared to taxa that were not associated with peridotites. Collectively, these findings indicate that the unique geochemical nature of the peridotite-hosted ecosystem has selected for H2-metabolizing, rock-associated taxa that can increase anabolism under high H2 concentrations. Because ultramafic rocks are widespread in slow-, and ultraslow-spreading oceanic lithosphere, continental margins, and subduction zones where H2 is formed in copious amounts, the link between H2 and carbon assimilation demonstrated here may be widespread within these geological settings

Mineral carbonation of peridotite fueled by magmatic degassing and melt impregnation in an oceanic transform fault

Most of the geologic CO2 entering Earth's atmosphere and oceans is emitted along plate margins. While C-cycling at mid-ocean ridges and subduction zones has been studied for decades, little attention has been paid to degassing of magmatic CO2 and mineral carbonation of mantle rocks in oceanic transform faults. We studied the formation of soapstone (magnesite-talc rock) and other magnesite-bearing assemblages during mineral carbonation of mantle peridotite in the St. Paul's transform fault, equatorial Atlantic. Clumped carbonate thermometry of soapstone yields a formation (or equilibration) temperature of 147 ± 13 °C which, based on thermodynamic constraints, suggests that CO2(aq) concentrations of the hydrothermal fluid were at least an order of magnitude higher than in seawater. The association of magnesite with apatite in veins, magnesite with a δ13C of -3.40 ± 0.04‰, and the enrichment of CO2 in hydrothermal fluids point to magmatic degassing and melt-impregnation as the main source of CO2. Melt-rock interaction related to gas-rich alkali olivine basalt volcanism near the St. Paul's Rocks archipelago is manifested in systematic changes in peridotite compositions, notably a strong enrichment in incompatible elements with decreasing MgO/SiO2. These findings reveal a previously undocumented aspect of the geologic carbon cycle in one of the largest oceanic transform faults: Fueled by magmatism in or below the root zone of the transform fault and subsequent degassing, the fault constitutes a conduit for CO2-rich hydrothermal fluids, while carbonation of peridotite represents a vast sink for the emitted CO2