Linkage bias in estimating the association between childhood exposures and propensity to become a mother: an example of simple sensitivity analyses

Summary.  Record linkage is a powerful tool to obtain individual follow-up information that is held in routinely collected databases. However, this method is potentially limited not only by the quality of the original data but also by the temporal and geographic coverage of the routine data. Migration in particular is a factor that might introduce systematic bias even in analyses of data covering relatively large geographical areas. We describe a linkage application where emigration bias might be an issue and use the sensitivity analysis approach that has been described by Molenberghs and co-workers and Kenward and co-workers to assess the extent of this bias.     

Identifying and using critical success factors

This article focuses on defining and discussing the concept of critical success factors as input into the environment analysis, resource analysis, and strategy evaluation steps in the strategic planning/strategy development process. The reader is provided with eight possible sources of critical success factors including environmental analysis, analysis of industry structure, industry/business experts, analysis of competition, analysis of dominant firm in the industry, company assessment, temporal/intuitive factors and PIMS results. Examples of CSF's from various sources are provided and a scheme by which the reader can assess the relative importance of identified CSF's is presented.     

A reducible four-parameter system of model life tables

Abstract In this paper a four-parameter extension of Brass's relational system of model life tables is suggested that (1) matches a wide range of empirical age patterns of mortality, (2) is easy to apply, especially to partial life tables, and (3) contains demographically meaningful parameters. A test of the model on a set of 62 empirical life tables indicates that four parameters are necessary and sufficient for fitting a wide range of mortality patterns. A further test on an historical series of Swedish life tables reveals a consistent pattern of mortality change. Examination of the parameters for a set of geographicallyrelated life tables suggests a way to define families of life tables. Identification of such temporal and spatial relationships allows the model to be reduced to a form with twoor three-parameters for application to incomplete or inaccurate data.     

Earnings per share is a poor indicator of performance

One of the greatest dangers in corporate financial planning is failing to separate investment decision making from financial policy, because poor quality investments can appear to be desirable as a result of the particular financing vehicle employed. Management's focus of attention should not be rates of growth and earnings per share or return on net worth. Rather, the most important measure of corporate performance is the rate of return on total capital employed. The paper identifies the dangers of employing an earnings per share criterion for evaluating corporate performance, and suggests an alternative: focusing on a company's free cash flow, net operating profits after taxes minus the amount of new capital investment required in order to generate future profits. The author presents an analytical framework employing his free cash flow concept which can be applied to pricing and financing acquisitions.     

Improved Bounds on Relaxations of a Parallel Machine Scheduling Problem

We consider the problem of scheduling n jobs withrelease dates on m identical parallel machines to minimize the average completion time of the jobs. We prove that the ratio of the average completion time of the optimal nonpreemptive schedule to that of the optimal preemptive schedule is at most 7/3, improving a bound of Shmoys and Wein.     

THE DISADVANTAGE OF A GOOD REPUTATION: Disney as a Target for Social Problems Claims

Social scientists generally presume that a good reputation has advantages. Yet the Walt Disney Corporation, a firm that has long benefited from a reputation for producing wholesome popular culture, attracts more than its share of efforts to link it to various social problems. In particular, conservative moralists argue that Disney in fact produces morally questionable products, progressive critics claim that Disney's messages help preserve social inequities, and social scientists criticize Disney for fostering inauthentic and alienating entertainment. These claims are a form of blowback—negative reactions to the firm's positive reputation. While blowback makes it easier to construct social problems claims, a good reputation remains a significant resource in deflecting these criticisms.     

Statistics of Primes (and Probably Twin Primes) Satisfy Taylor's Law from Ecology

Taylor's law, which originated in ecology, states that, in sets of measurements of population density, the sample variance is approximately proportional to a power of the sample mean. Taylor's law has been verified for many species ranging from bacterial to human. Here, we show that the variance V(x) and the mean M(x) of the primes not exceeding a real number x obey Taylor's law asymptotically for large x. Specifically, V(x) ～ (1/3)(M(x))² as x → ∞. This apparently new fact about primes shows that Taylor's law may arise in the absence of biological processes, and that patterns discovered in biological data can suggest novel questions in number theory. If the Hardy-Littlewood twin primes conjecture is true, then the identical Taylor's law holds also for twin primes. Taylor's law holds in both instances because the primes (and the twin primes, given the conjecture) not exceeding x are asymptotically uniformly distributed on the integers in [2, x]. Hence, asymptotically M(x) ～ x/2, V(x) ～ x²/12. Higher-order moments of the primes (twin primes) not exceeding x satisfy a generalized Taylor's law. The 11,078,937 primes and 813,371 twin primes not exceeding 2 × 10⁸ illustrate these results.     

Investment-Promoting Policies in the Presence of International Interactions

Investment-promoting policies in a small open economy are analyzed by means of a dynamic applied general equilibrium model with overlapping generations. Simulations of a decrease of the corporate income tax rate and an increase of the investment tax credit rate are discussed and compared. This paper examines in particular the extent to which international trade and capital flows interfere in both tax policies. The modeling of overlapping generations allows moreover to identify the winners and losers of these reforms. It is shown that the subsidy policy is preferred to the profit tax policy when a small open economy seeks to stimulate capital formation.     

Replacement Migration: Is it a Solution to Declining and Aging Populations?

Population and Environment - This report looks at the recent publication prepared by the UN Population Division which examines the demographic situation in most advanced nations, but especially in...