The Bibliometric Properties of Article Readership Information

The NASA Astrophysics Data System (ADS), along with astronomy's journals and data centers (a collaboration dubbed URANIA), has developed a distributed on-line digital library which has become the dominant means by which astronomers search, access and read their technical literature. Digital libraries such as the NASA Astrophysics Data System permit the easy accumulation of a new type of bibliometric measure, the number of electronic accesses (``reads'') of individual articles. We explore various aspects of this new measure. We examine the obsolescence function as measured by actual reads, and show that it can be well fit by the sum of four exponentials with very different time constants. We compare the obsolescence function as measured by readership with the obsolescence function as measured by citations. We find that the citation function is proportional to the sum of two of the components of the readership function. This proves that the normative theory of citation is true in the mean. We further examine in detail the similarities and differences between the citation rate, the readership rate and the total citations for individual articles, and discuss some of the causes. Using the number of reads as a bibliometric measure for individuals, we introduce the read-cite diagram to provide a two-dimensional view of an individual's scientific productivity. We develop a simple model to account for an individual's reads and cites and use it to show that the position of a person in the read-cite diagram is a function of age, innate productivity, and work history. We show the age biases of both reads and cites, and develop two new bibliometric measures which have substantially less age bias than citationsComment: ADS bibcode: 2005JASIS..56..111K This is the second paper (the first is Worldwide Use and Impact of the NASA Astrophysics Data System Digital Library) from the original article The NASA Astrophysics Data System: Sociology, Bibliometrics, and Impact, which went on-line in the summer of 200

How High are the Giants' Shoulders: An Empirical Assessment of Knowledge Spillovers and Creative Destruction in a Model of Economic Growth

The pace of industrial innovation and growth is shaped by many forces that interact in complicated ways. Profit-maximizing firms pursue new ideas to obtain market power, but the pursuit of the same goal by other means that even successful inventions art eventually superseded by others; this known as creative destruction. New ideas not only yield new goods but also enrich the stock of knowledge of society and its potential to produce new ideas. To a great extent this knowledge is non-excludable, making research and inventions the source of powerful spillovers. The extent of spillovers depends on the rate at which new ideas outdate old ones, that is on the endogenous technological obsolescence of ideas, and on the rate at which knowledge diffuses among inventors. In this paper we build a simple model that allows us to organize our search for the empirical strength of the concepts emphasized above. We then use data on patents and patent citations as empirical counterparts of new ideas and knowledge spillovers, respectively, to estimate the model parameters. We find estimates of the annual rate of creative destruction in the range of 2 to 7 percent for the decade of the 1970s, which rates for individual sectors as high as 25 percent. For technological obsolescence, we find an increase over the century from about 3 percent per year to about 12 percent per year in 1990, with a noticeable plateau in the l970s. We find the rate of diffusion of knowledge to be quite rapid, with the mean lag between I and 2 years. Lastly, we find that the potency of spillovers from old ideas to new knowledge generation (as evidenced by patent citation rate) has been declining over the century: the resulting decline in the effective public stock of knowledge available to new inventors is quite consistent with the observed decline in the average private productivity of research inputs

Long-Period Employment, Service Innovation, and Profit

Firms face various types of obsolescence risk. We posit that workers\u27 firm-specific experience increases labor productivity and prevents obsolescence. The return on firm-specific experience increases with employment period. However, no study has examined whether human resource development with a long-term vision drives business innovation and enables a firm to remain competitive. We use obsolescence risk to analyze the relationship between the returns on long-period employment and profit. We find that when firm-specific experience provides sufficiently large returns and the risk of obsolescence is low, the expected profit is greater for long-period employment than short-period employment

Occupational Training in High School: When Does it Pay Off?

[Excerpt] About half of all youth either do not complete high school or end their formal education with the high school diploma. Even higher proportions of minority, disadvantaged and handicapped youth do not enter postsecondary education. Should public schools offer these youth occupationally specific education and training? If so, what form should this education take? Should the goal of the occupational component of high school vocational education be occupationally specific skills, career awareness, basic skills or something else? What should be the relationship between programs providing occupationally specific training and the employers who hire their graduates

The Vintage Effect in TPF-Growth: An Analysis of the Age Structure of Capital

The age structure of capital plays an important role in the measurement of productivity.It has been argued that the slowdown in the 1970 s can be ascribed to the aging of the stock of capital.In this paper we incorporate the age structure in productivity measurement.One proposition proves that Nelson s (1964) formula is only an approximation.Our final proposition shows that inclusion of the vintage effect prompts an upward correction of measured productivity growth in times of an aging stock of capital.Here capital ages if the investment/capital ratio falls short of the inverse of the capital age, as a first proposition shows.The analysis rests on a rigorous accounting for vintages.We translate the Bureau of Economic Analysis age of capital data into a measure of rates of obsolescence.Empirically, the correction of productivity growth for the vintage effect requires an estimate of the obsolescence and depreciation parameters on the basis of age data.The results indicate that the use of capital stock in efficiency units does cause some smoothing of Total Factor Productivity growth over time.In the 1950s, when investment accelerated, the vintage-adjusted capital growth rate well exceeded the BEA growth rate, and vintageadjusted TFP growth is significantly lower than unadjusted TFP growth.The measured productivity slowdown of the 1970s is somewhat ameliorated.capital;productivity;growth;expenditure;tfp

Ideas driven growth: the OECD evidence

This paper estimates the parameters of the ideas production function crucial to recent ideas-driven growth models. Using U. S. patents granted to residents in OECD countries in order to construct the stock of commercially used ideas, we provide evidence for two main findings. First, at the level of the production of ideas, we find evidence of increasing returns to scale in the stock of ideas and number of researchers, but marginal decreasing returns in each one of these factors. Second, we provide evidence of the association between ideas growth and economic growth, for the OECD as a whole, in the long run.Innovation; spillovers; ideas-driven growth; patents; public intervention

Technological Progress, Obsolescence and Depreciation

We construct a vintage capital model à la Whelan (2002) with both exogenous embodied and disembodied technical progress, and variable utilization of each vintage. The lifetime of capital goods is endogenous and it relies on the associated maintenance costs. We study the properties of the balanced growth paths. First, we show that the lifetime of capital is an increasing (resp. decreasing) function of the rate of disembodied (resp.embodied) technical progress. Second, we show that both the use-related depreciation rate and the scrapping rate incease when embodied technical progress accelerates. However, the latter drops when disembodied technical progress accelerates while the former remains unaffected. A key feature of our model is that the age-related depreciation rate does depend on the obsolescence rate in sharp contrast to the neoclassical model.Vintage capital; operation costs; embodied technical progress; age-related depreciation; obsolescence