Knowledge that Transforms

T HE overall impact of poor health on earnings is large the average disabled man aged 18 to 64 years suffers a 37% reduction in yearly earnings. This loss is the result of the effects of poor health on all the components of earnings: labor force participation, weeks worked per year, hours worked per week, and earnings per hour. In each case there is a substantial effect of health, not just when a comparison is made between well and sick persons, but also when adjustments are made to account for the different socio-economic characteristics of the two groups. This analysis not only provides estimates of the effect of health on each component of earnings, but also the aggregate earnings loss attributable to long term disability 23 billion dollars in 1966. The first section outlines some of the previous analyses concerning the effects of health on the various components of earnings and briefly describes the data and method used in this study. The effects of health are usually measured by comparing the status of persons who are well with those who are disabled. The second and third sections offer this comparison as well as the true effects of health which are based on the difference between the current status of the disabled and their estimated status, based on how they would have behaved had they been well, taking into account the different socioeconomic characteristics of the well and disabled groups. The first of these two sections provides the comparisons for each of the components of earnings. As the analysis is carried out for subsamples of men and women, and blacks and whites, it is possible to examine the different ways in which disability affects different groups. The second section of the pair continues the analysis in terms of a more aggregate measure the overall loss of earnings to the economy within a year. A final section provides a brief summary and an outline of the major findings and conclusions.

ONE of the most important stages of the process of technological change is diffusion. Since the rate of diffusion is the rate at which a new technique is actually put into use, it is a critical determinant of the rate of growth of productivity. If certain types of firms and industries are quicker to diffuse a new, more efficient technique, they are quicker to attain the resulting increases in productivity. It would certainly seem useful, particularly from the point of view of public policy, to develop convincing empirical evidence concerning the characteristics of such firms and industries. Previous studies have provided a sound foundation for studying diffusion.' This article attempts to build on this foundation by observing the diffusion of one of the twentieth century's most important manufacturing innovations numerically controlled machine tools in ten industries. One purpose of this study is to provide a further test of the usefulness of the model of the imitation process developed by Mansfield (1961, 1968). In particular, we are interested in seeing how well his model can explain the increase over time in the percentage of new machine tools purchased that have numerical controls. This involves a different measure of the rate of diffusion than the measures investigated to date by other researchers. Also, we look at the effects on the rate of diffusion of an industry's market structure and the extent of its investment in R&D. Although previous studies have touched on these factors, this study goes further in measuring their effects than any previous work. Further, we investigate how the characteristics of the early users of numerical control (NC) differed from those that were slower to use it, and we study the determinants of the intrafirm rate of diffusion.

THIS paper is an empirical study attempting to ascertain those factors that influence the firm's choice of a debt-equity ratio. Baxter and Cragg (1970), have published an empirical study that is similar in nature to this one. However, this paper differs from theirs in several important respects. First, we deal explicitly with the relationship between the overall debtequity ratio of the firm and the firm's choice of new financing. Secondly, we include the notion that the risk premiums required on bonds issued may differ among firms or between years. Finally, we include as a variable the corporate tax rate for each year. In section I we present the statistical model. A description of the independent variables used in the empirical study is presented in section II. Section III contains the results of our study plus implications and conclusions.

THE age profile of individual asset holdings is frequently supposed to follow a hump pattern, increasing during the working lifetime and declining in later years. The theoretical explanation of such a relationship is firmly established, since it is a characteristic feature of life-cycle saving models. However, the empirical evidence has never been critically examined. A number of studies based on sample survey information have been regarded as confirming this hump pattern, but on closer examination the evidence is far from conclusive. Moreover the survey results conflict fundamentally with alternative estimates of the age-wealth relationship derived from estate tax data. This paper begins in section II by examining this basic conflict. In the following section the relevance of cross-section studies is questioned, and a cohort is identified whose lifetime wealth characteristics can be studied. The sequence of observed wealth distributions for this cohort is obtained by selecting successive ten years age groups from the Estate duty statistics at intervals of a decade. Section IV is devoted to an analysis of the variation in the composition of any cohort as it ages. These composition changes arise from the fact that wealthier individuals have a lower mortality rate and therefore tend to become a larger proportion of the surviving cohort independently of accumulation behaviour. In these circumstances the characteristics of the representative individual will not necessarily correspond to the representative behaviour of the group. It is, however, possible to correct for this change in composition so that the empirical estimates can be compared with the predictions of economic theory.

Industrial demand for energy is essentially a derived demand: the firm's demand for energy is an input is derived from demand for the firm's output. Inputs other than energy typically also enter the firm's production process. Since firms tend to choose that bundle of inputs which minimized the total cost of producing a giving level of output, the derived demand for inputs, including energy, depends on the level of output, the submitions possibilies among inputs allow by production technology, and the relative prices of all inputs.

Journal Article A Note on the Concavity of the Mean-Variance Problem Get access David Sibley David Sibley Yale University Search for other works by this author on: Oxford Academic Google Scholar The Review of Economic Studies, Volume 42, Issue 3, July 1975, Pages 479–481, https://doi.org/10.2307/2296861 Published: 01 July 1975

Journal Article The Aggregate Excess Demand Correspondence and the Structure of Economies with Externalities Get access D. T. Scheffman D. T. Scheffman University of Western Ontario Search for other works by this author on: Oxford Academic Google Scholar The Review of Economic Studies, Volume 42, Issue 4, October 1975, Pages 597–604, https://doi.org/10.2307/2296796 Published: 01 October 1975